File: pruned_state_space_system.m

package info (click to toggle)
dynare 4.6.3-4
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 74,896 kB
  • sloc: cpp: 98,057; ansic: 28,929; pascal: 13,844; sh: 5,947; objc: 4,236; yacc: 4,215; makefile: 2,583; lex: 1,534; fortran: 877; python: 647; ruby: 291; lisp: 152; xml: 22
file content (1222 lines) | stat: -rw-r--r-- 71,575 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
function pruned_state_space = pruned_state_space_system(M, options, dr, indy, nlags, useautocorr, compute_derivs)
% Set up the pruned state space ABCD representation:
%   z =      c + A*z(-1) + B*inov
%   y = ys + d + C*z(-1) + D*inov
% References: 
% - Andreasen, Martin M., Jesús Fernández-Villaverde and Juan F. Rubio-Ramírez (2018):
%   "The Pruned State-Space System for Non-Linear DSGE Models: Theory and Empirical Applications",
%   Review of Economic Studies, Volume 85, Issue 1, Pages 1–49.
% - Mutschler, Willi (2018): "Higher-order statistics for DSGE models",
%   Econometrics and Statistics, Volume 6, Pages 44-56.
% =========================================================================
% INPUTS
%   M:            [structure] storing the model information
%   options:      [structure] storing the options
%   dr:           [structure] storing the results from perturbation approximation
%   indy:         [vector]    index of control variables in DR order
%   nlags:        [integer]   number of lags in autocovariances and autocorrelations
%   useautocorr:  [boolean]   true: compute autocorrelations
% -------------------------------------------------------------------------
% OUTPUTS
% pruned_state_space: [structure] with the following fields:
%   indx:       [x_nbr by 1]
%                 index of state variables
%   indy:       [y_nbr by 1]
%                 index of control variables
%   A:          [z_nbr by z_nbr]
%                 state space transition matrix A mapping previous states to current states
%   B:          [z_nbr by inov_nbr]
%                 state space transition matrix B mapping current inovations to current states
%   c:          [z_nbr by 1]
%                 state space transition matrix c mapping constants to current states
%   C:          [y_nbr by z_nbr]
%                 state space measurement matrix C mapping previous states to current controls
%   D:          [y_nbr by inov_nbr]
%                 state space measurement matrix D mapping current inovations to current controls
%   d:          [y_nbr by 1]
%                 state space measurement matrix d mapping constants to current controls
%   Var_inov    [inov_nbr by inov_nbr]
%                 contemporenous covariance matrix of innovations, i.e. E[inov*inov']
%   Var_z       [z_nbr by z_nbr]
%                 contemporenous covariance matrix of states z
%   Var_y       [y_nbr by y_nbr]
%                 contemporenous covariance matrix of controls y
%   Var_yi      [y_nbr by y_nbr by nlags]
%                 autocovariance matrix of controls y
%   Corr_y      [y_nbr by y_nbr]
%                 contemporenous correlation matrix of controls y
%   Corr_yi     [y_nbr by y_nbr by nlags]
%                 autocorrelation matrix of controls y
%   E_y         [y_nbr by 1] 
%                 unconditional theoretical mean of control variables y
%
% if compute_derivs == 1, then the following additional fields are outputed:
%   dA:         [z_nbr by z_nbr by totparam_nbr]
%                 parameter Jacobian of A
%   dB:         [z_nbr by inov_nbr by totparam_nbr]
%                 parameter Jacobian of B
%   dc:         [z_nbr by totparam_nbr]
%                 parameter Jacobian of c
%   dC:         [y_nbr by z_nbr by totparam_nbr]
%                 parameter Jacobian of C
%   dD:         [y_nbr by inov_nbr by totparam_nbr]
%                 parameter Jacobian of D
%   dd:         [y_nbr by totparam_nbr]
%                 parameter Jacobian of d
%   dVar_inov   [inov_nbr by inov_nbr by totparam_nbr]
%                 parameter Jacobian of Var_inov
%   dVar_z      [z_nbr by z_nbr by totparam_nbr]
%                 parameter Jacobian of Var_z
%   dVar_y      [y_nbr by y_nbr by totparam_nbr]
%                 parameter Jacobian of Var_y
%   dVar_yi     [y_nbr by y_nbr by nlags by totparam_nbr]
%                 parameter Jacobian of Var_yi
%   dCorr_y     [y_nbr by y_nbr by totparam_nbr]
%                 parameter Jacobian of Corr_y
%   dCorr_yi    [y_nbr by y_nbr by nlags by totparam_nbr]
%                 parameter Jacobian of Corr_yi
%   dE_y        [y_nbr by totparam_nbr]
%                 parameter Jacobian of E_y
% -------------------------------------------------------------------------
% This function is called by
%   * get_identification_jacobians.m
%   * identification_numerical_objective.m
% -------------------------------------------------------------------------
% This function calls
%   * allVL1.m
%   * commutation.m
%   * disclyap_fast.m
%   * duplication.m
%   * lyapunov_symm.m
%   * prodmom
%   * prodmom_deriv
%   * Q6_plication
%   * quadruplication.m
%   * vec.m
% =========================================================================
% Copyright (C) 2019-2020 Dynare Team
%
% This file is part of Dynare.
%
% Dynare is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% Dynare is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
% =========================================================================

%% MAIN IDEA:
%   Decompose the state vector x into first-order effects xf, second-order 
%   effects xs, and third-order effects xrd, i.e. x=xf+xs+xrd. Then, Dynare's
%   perturbation approximation for the state vector up to third order
%   (with Gaussian innovations u, i.e. no odd moments, hxxs=huus=hxus=hsss=0) is:
%   x = hx*( xf(-1)+xs(-1)+xrd(-1) )
%     + hu*u
%     + 1/2*hxx*kron( xf(-1)+xs(-1)+xrd(-1) , xf(-1)+xs(-1)+xrd(-1) )
%     + hxu*kron( xf(-1)+xs(-1)+xrd(-1) , u )
%     + 1/2*huu*kron( u , u )
%     + 1/2*hss*sig^2
%     + 1/6*hxxx*kron( kron( xf(-1)+xs(-1)+xrd(-1) , xf(-1)+xs(-1)+xrd(-1) ) , xf(-1)+xs(-1)+xrd(-1) )
%     + 1/6*huuu*kron( kron( u , u ) , u )
%     + 3/6*hxxu*kron( kron( xf(-1)+xs(-1)+xrd(-1) , xf(-1)+xs(-1)+xrd(-1) ) , u )
%     + 3/6*hxuu*kron( kron( xf(-1)+xs(-1)+xrd(-1) , u ) , u)
%     + 3/6*hxss*( xf(-1)+xs(-1)+xrd(-1) )*sig^2
%     + 3/6*huss*u*sig^2
%   where:
%     hx  = dr.ghx(indx,:);    hu  = dr.ghu(indx,:);
%     hxx = dr.ghxx(indx,:);   hxu = dr.ghxu(indx,:);   huu = dr.ghuu(indx,:);   hss = dr.ghs2(indx,:);
%     hxxx = dr.ghxxx(indx,:); huuu = dr.ghuuu(indx,:); hxxu = dr.ghxxu(indx,:); hxuu = dr.ghxxu(indx,:); hxss = dr.ghxss(indx,:); huss = dr.ghuss(indx,:);
%     and similarly for control variables:
%   y = gx*( xf(-1)+xs(-1)+xrd(-1) )
%     + gu*u
%     + 1/2*gxx*kron( xf(-1)+xs(-1)+xrd(-1) , xf(-1)+xs(-1)+xrd(-1) )
%     + gxu*kron( xf(-1)+xs(-1)+xrd(-1) , u )
%     + 1/2*guu*kron( u , u )
%     + 1/2*gss*sig^2
%     + 1/6*gxxx*kron( kron( xf(-1)+xs(-1)+xrd(-1) , xf(-1)+xs(-1)+xrd(-1) ) , xf(-1)+xs(-1)+xrd(-1) )
%     + 1/6*guuu*kron( kron( u , u ) , u )
%     + 3/6*gxxu*kron( kron( xf(-1)+xs(-1)+xrd(-1) , xf(-1)+xs(-1)+xrd(-1) ) , u )
%     + 3/6*gxuu*kron( kron( xf(-1)+xs(-1)+xrd(-1) , u ) , u)
%     + 3/6*gxss*( xf(-1)+xs(-1)+xrd(-1) )*sig^2
%     + 3/6*guss*u*sig^2
%   where:
%     gx  = dr.ghx(indy,:);    gu  = dr.ghu(indy,:);
%     gxx = dr.ghxx(indy,:);   gxu = dr.ghxu(indy,:);   guu = dr.ghuu(indy,:);   gss = dr.ghs2(indy,:);
%     gxxx = dr.ghxxx(indy,:); guuu = dr.ghuuu(indy,:); gxxu = dr.ghxxu(indy,:); gxuu = dr.ghxxu(indy,:); gxss = dr.ghxss(indy,:); guss = dr.ghuss(indy,:);
%
%   PRUNING means getting rid of terms higher than the approximation order, i.e.
%         - involving fourth-order effects:  kron(xf,xrd), kron(xs,xs), kron(xrd,xf), kron(xrd,u), 
%                                            kron(kron(xf,xf),xs), kron(kron(xf,xs),xf), kron(kron(xs,xf),xf)
%                                            kron(kron(xf,xs),u), kron(kron(xs,xf),u)
%                                            kron(kron(xs,u),u)
%                                            xs*sig^2
%         - involving fifth-order effects:   kron(xs,xrd), kron(xrd,xs),
%                                            kron(kron(xf,xf),xrd), kron(kron(xf,xs),xs), kron(kron(xf,xrd),xf), kron(kron(xs,xf),xs), kron(kron(xs,xs),xf), kron(kron(xrd,xf),xf)
%                                            kron(kron(xf,xrd),u), kron(kron(xs,xs),u), kron(kron(xrd,xf),u)
%                                            kron(kron(xrd,u),u)
%                                            xrd*sig^2
%         - involving sixth-order effects:   kron(xrd,xrd),
%                                            kron(kron(xf,xs),xrd), kron(kron(xf,xrd),xs), kron(kron(xs,xrd),xrd), kron(kron(xs,xs),xs), kron(kron(xs,xrd),xf), kron(kron(xf,xf),xs), kron(kron(xrd,xs),xf)
%                                            kron(kron(xs,xrd),u), kron(kron(xrd,xs),u)
%         - involving seventh-order effects: kron(kron(xf,xrd),xrd), kron(kron(xs,xs),xrd), kron(kron(xs,xrd),xs), kron(kron(xrd,xf),xrd), kron(kron(xrd,xs),xs), kron(kron(xrd,xrd),xf)
%                                            kron(kron(xrd,xrd),u)
%         - involving eighth-order effects:  kron(kron(xs,xrd),xrd), kron(kron(xrd,xs),xrd), kron(kron(xrd,xrd),xs)
%         - involving ninth-order effects:   kron(kron(xrd,xrd),xrd)
%   Note that u is treated as a first-order effect and the perturbation parameter sig as a variable.
%
% SUMMARY OF LAW OF MOTIONS: Set up the law of motions for the individual effects, but keep only effects of same order
%   Notation: I_n=eye(n) and K_m_n=commutation(m,n)
%
%   First-order effects: keep xf and u
%       xf = hx*xf(-1) + hu*u
%       Note that we 
%
%   Second-order effects: keep xs, kron(xf,xf), kron(u,u), kron(xf,u), and sig^2
%       xs = hx*xs(-1) + 1/2*hxx*kron(xf(-1),xf(-1)) + 1/2*huu*(kron(u,u)-Sigma_e(:)+Sigma_e(:)) + hxu*kron(xf(-1),u) + 1/2*hss*sig^2%     
%
%   Third-order effects: keep xrd, kron(xf,xs), kron(xs,xf), kron(xs,u), kron(kron(xf,xf),xf), kron(kron(u,u),u), kron(kron(xf,xf),u), kron(kron(xf,u),u), xf*sig^2, u*sig^2
%       xrd = hx*xrd(-1) + 1/2*hxx*(kron(xf(-1),xs(-1))+kron(xs(-1),xf(-1))) + hxu*kron(xs(-1),u) + 1/6*hxxx*kron(xf(-1),kron(xf(-1),xf(-1))) + 1/6*huuu*kron(u,kron(u,u)) + 3/6*hxxu*kron(xf(-1),kron(xf(-1),u)) + 3/6*hxuu*kron(xf(-1),kron(u,u)) + 3/6*hxss*xf(-1)*sig^2 + 3/6*huss*u*sig^2
%     Simplified (due to symmetry in hxx):
%       xrd = hx*xrd(-1) + hxx*(kron(xf(-1),xs(-1)) + hxu*kron(xs(-1),u) + 1/6*hxxx*kron(xf(-1),kron(xf(-1),xf(-1))) + 1/6*huuu*kron(u,kron(u,u)) + 3/6*hxxu*kron(xf(-1),kron(xf(-1),u)) + 3/6*hxuu*kron(xf(-1),kron(u,u)) + 3/6*hxss*xf(-1)*sig^2 + 3/6*huss*u*sig^2%     
%
%   Auxiliary equation kron(xf,xf) to set up the VAR(1) pruned state space system
%       kron(xf,xf) = kron(hx,hx)*kron(xf(-1),xf(-1)) + kron(hu,hu)*(kron(u,u)-Sigma_e(:)+Sigma_e(:)) + kron(hx,u)*kron(xf(-1),u) + kron(u,hx)*kron(u,xf(-1))
%     Simplified using commutation matrix:
%       kron(xf,xf) = kron(hx,hx)*kron(xf(-1),xf(-1)) + (I_xx+K_x_x)*kron(hx,hu)*kron(xf(-1),u) + kron(hu,hu)*kron(u,u)
%
%   Auxiliary equation kron(xf,xs) to set up the VAR(1) pruned state space system
%       kron(xf,xs) = kron(hx,hx)*kron(xf(-1),xs(-1)) + kron(hu,hx)*kron(u,xs(-1))
%                   + kron(hx,1/2*hxx)*kron(kron(xf(-1),xf(-1)),xf(-1)) + kron(hu,1/2*hxx)*kron(kron(u,xf(-1)),xf(-1))
%                   + kron(hx,1/2*huu)*kron(kron(xf(-1),u),u) + kron(hu,1/2*huu)*kron(kron(u,u),u)
%                   + kron(hx,hxu)*kron(kron(xf(-1),xf(-1)),u) + kron(hu,hxu)*kron(kron(u,xf(-1)),u)
%                   + kron(hx,1/2*hss)*xf(-1)*sig^2 + kron(hu,1/2*hss)*u*sig^2
%     Simplified using commutation matrix:
%       kron(xf,xs) = kron(hx,hx)*kron(xf(-1),xs(-1))
%                   + K_x_x*kron(hx,hu)*kron(xs(-1),u)
%                   + kron(hx,1/2*hxx)*kron(kron(xf(-1),xf(-1)),xf(-1))
%                   + ( kron(hx,hxu) + K_x_x*kron(1/2*hxx,hu) )*kron(kron(xf(-1),xf(-1)),u)
%                   + ( kron(hx,1/2*huu) + K_x_x*kron(hxu,hu) )*kron(kron(xf(-1),u),u)
%                   + kron(hu,1/2*huu)*kron(kron(u,u),u)
%                   + kron(hx,1/2*hss)*xf(-1)*sig^2
%                   + kron(hu,1/2*hss)*u*sig^2
%
%   Auxiliary equation kron(kron(xf,xf),xf) to set up the VAR(1) pruned state space system
%       kron(kron(xf,xf),xf) = kron(kron(hx,hx),hx)*kron(kron(xf(-1),xf(-1)),xf(-1))
%                            + kron(kron(hx,hu),hx)*kron(kron(xf(-1),u),xf(-1))
%                            + kron(kron(hx,hx),hu)*kron(kron(xf(-1),xf(-1)),u)
%                            + kron(kron(hx,hu),hu)*kron(kron(xf(-1),u),u)
%                            + kron(kron(hu,hx),hx)*kron(kron(u,xf(-1)),xf(-1))
%                            + kron(kron(hu,hu),hx)*kron(kron(u,u),xf(-1))
%                            + kron(kron(hu,hx),hu)*kron(kron(u,xf(-1)),u)
%                            + kron(kron(hu,hu),hu)*kron(kron(u,u),u)
%     Simplified using commutation matrix:
%       kron(kron(xf,xf),xf) = kron(kron(hx,hx),hx)*kron(kron(xf(-1),xf(-1)),xf(-1))
%                            + ( kron(kron(hx,hx),hu) + K_xx_x*kron(hx,(I_xx+K_x_x)*kron(hx,hu)) )*kron(kron(xf(-1),xf(-1)),u)
%                            + ( kron((I_xx+K_x_x)*kron(hx,hu),hu) + K_xx_x*kron(kron(hx,hu),hu) )*kron(kron(xf(-1),u),u)
%                            + kron(kron(hu,hu),hu)*kron(kron(u,u),u)
%
%   Law of motion for control variables y (either VAROBS variables or if no VAROBS statement is given then for all endogenous variables)
%       y = steady_state(y)
%         + gx*( xf(-1)+xs(-1)+xrd(-1) )
%         + gu*u
%         + 1/2*gxx*kron(xf(-1),xf(-1)) + gxx*kron(xf(-1),xs(-1))
%         + gxu*kron(xf(-1),u) + gxu*kron(xs(-1),u)
%         + 1/2*guu*(kron(u,u)-Sigma_e+Sigma_e)
%         + 1/2*gss*sig^2
%         + 1/6*gxxx*kron(kron(xf(-1),xf(-1)),xf(-1))
%         + 1/6*guuu*kron(kron(u,u),u)
%         + 3/6*gxxu*kron(kron(xf(-1),xf(-1),u)
%         + 3/6*gxuu*kron(kron(xf(-1),u),u)
%         + 3/6*gxss*xf(-1)*sig^2
%         + 3/6*guss*u*sig^2
%
% See code below how z and inov are defined at first, second, and third order,
% and how to set up A, B, C, D and compute unconditional first and second moments of inov, z and y


%% Auxiliary indices and objects
order = options.order;
if isempty(options.qz_criterium)
    % set default value for qz_criterium: if there are no unit roots one can use 1.0
    % If they are possible, you may have have multiple unit roots and the accuracy 
    % decreases when computing the eigenvalues in lyapunov_symm. Hence, we normally use 1+1e-6
    % Note that unit roots are only possible at first-order, at higher order we set it to 1
    options.qz_criterium = 1+1e-6;
end
indx = [M.nstatic+(1:M.nspred) M.endo_nbr+(1:size(dr.ghx,2)-M.nspred)]';
if isempty(indy)
    indy = (1:M.endo_nbr)'; %by default select all variables in DR order
end
u_nbr    = M.exo_nbr;
x_nbr    = length(indx);
y_nbr    = length(indy);
Yss      = dr.ys(dr.order_var);
hx       = dr.ghx(indx,:);
gx       = dr.ghx(indy,:);
hu       = dr.ghu(indx,:);
gu       = dr.ghu(indy,:);
E_uu     = M.Sigma_e; %this is E[u*u']

if compute_derivs
    stderrparam_nbr = length(dr.derivs.indpstderr);
    corrparam_nbr   = size(dr.derivs.indpcorr,1);
    modparam_nbr    = length(dr.derivs.indpmodel);
    totparam_nbr    = stderrparam_nbr+corrparam_nbr+modparam_nbr;
    dYss   = dr.derivs.dYss;
	dhx    = dr.derivs.dghx(indx,:,:);
    dgx    = dr.derivs.dghx(indy,:,:);
	dhu    = dr.derivs.dghu(indx,:,:);
    dgu    = dr.derivs.dghu(indy,:,:);
	dE_uu  = dr.derivs.dSigma_e;
end

% first-order approximation indices for extended state vector z and extended innovations vector inov 
id_z1_xf    = (1:x_nbr);
id_inov1_u  = (1:u_nbr);
if order > 1
    % second-order approximation indices for extended state vector z and extended innovations vector inov 
    id_z2_xs      = id_z1_xf(end)     + (1:x_nbr);
    id_z3_xf_xf   = id_z2_xs(end)     + (1:x_nbr*x_nbr);
    id_inov2_u_u  = id_inov1_u(end)   + (1:u_nbr*u_nbr);
    id_inov3_xf_u = id_inov2_u_u(end) + (1:x_nbr*u_nbr);

    hxx = dr.ghxx(indx,:);
    gxx = dr.ghxx(indy,:);
    hxu = dr.ghxu(indx,:);
    gxu = dr.ghxu(indy,:);
    huu = dr.ghuu(indx,:);
    guu = dr.ghuu(indy,:);
    hss = dr.ghs2(indx,:);
    gss = dr.ghs2(indy,:);
    if compute_derivs        
        dhxx = dr.derivs.dghxx(indx,:,:);
        dgxx = dr.derivs.dghxx(indy,:,:);
        dhxu = dr.derivs.dghxu(indx,:,:);
        dgxu = dr.derivs.dghxu(indy,:,:);
        dhuu = dr.derivs.dghuu(indx,:,:);
        dguu = dr.derivs.dghuu(indy,:,:);
        dhss = dr.derivs.dghs2(indx,:);
        dgss = dr.derivs.dghs2(indy,:);
    end
end
if order > 2
    % third-order approximation indices for extended state vector z and extended innovations vector inov 
    id_z4_xrd        = id_z3_xf_xf(end)      + (1:x_nbr);
    id_z5_xf_xs      = id_z4_xrd(end)        + (1:x_nbr*x_nbr);
    id_z6_xf_xf_xf   = id_z5_xf_xs(end)      + (1:x_nbr*x_nbr*x_nbr);
    id_inov4_xs_u    = id_inov3_xf_u(end)    + (1:x_nbr*u_nbr);
    id_inov5_xf_xf_u = id_inov4_xs_u(end)    + (1:x_nbr*x_nbr*u_nbr);
    id_inov6_xf_u_u  = id_inov5_xf_xf_u(end) + (1:x_nbr*u_nbr*u_nbr);
    id_inov7_u_u_u   = id_inov6_xf_u_u(end)  + (1:u_nbr*u_nbr*u_nbr);

    hxxx = dr.ghxxx(indx,:);
    gxxx = dr.ghxxx(indy,:);
    hxxu = dr.ghxxu(indx,:);
    gxxu = dr.ghxxu(indy,:);
    hxuu = dr.ghxuu(indx,:);
    gxuu = dr.ghxuu(indy,:);
    huuu = dr.ghuuu(indx,:);
    guuu = dr.ghuuu(indy,:);
    hxss = dr.ghxss(indx,:);
    gxss = dr.ghxss(indy,:);
    huss = dr.ghuss(indx,:);
    guss = dr.ghuss(indy,:);
    if compute_derivs
        dhxxx = dr.derivs.dghxxx(indx,:,:);
        dgxxx = dr.derivs.dghxxx(indy,:,:);
        dhxxu = dr.derivs.dghxxu(indx,:,:);
        dgxxu = dr.derivs.dghxxu(indy,:,:);
       	dhxuu = dr.derivs.dghxuu(indx,:,:);
        dgxuu = dr.derivs.dghxuu(indy,:,:);
        dhuuu = dr.derivs.dghuuu(indx,:,:);
        dguuu = dr.derivs.dghuuu(indy,:,:);
        dhxss = dr.derivs.dghxss(indx,:,:);
        dgxss = dr.derivs.dghxss(indy,:,:);
        dhuss = dr.derivs.dghuss(indx,:,:);
        dguss = dr.derivs.dghuss(indy,:,:);
    end
end

%% First-order state space system
% Auxiliary state vector z is defined by:          z    = [xf]
% Auxiliary innovations vector inov is defined by: inov = [u]
z_nbr       = x_nbr;
inov_nbr    = M.exo_nbr;
A           = hx;
B           = hu;
c           = zeros(x_nbr,1);
C           = gx;
D           = gu;
d           = zeros(y_nbr,1);
Varinov     = E_uu;
E_inovzlag1  = zeros(inov_nbr,z_nbr); %at first-order E[inov*z(-1)'] = 0
Om_z        = B*Varinov*B';
E_xf        = zeros(x_nbr,1);

lyapunov_symm_method = 1; %method=1 to initialize persistent variables
[Var_z,Schur_u] = lyapunov_symm(A, Om_z,... %at first-order this algorithm is well established and also used in th_autocovariances.m
                                options.lyapunov_fixed_point_tol, options.qz_criterium, options.lyapunov_complex_threshold,...
                                lyapunov_symm_method,...       
                                options.debug); %we use Schur_u to take care of (possible) nonstationary VAROBS variables in moment computations
%find stationary vars
stationary_vars = (1:y_nbr)';
if ~isempty(Schur_u)
    %base this only on first order, because if first-order is stable so are the higher-order pruned systems
    x = abs(gx*Schur_u);
    stationary_vars = find(all(x < options.Schur_vec_tol,2));
end

if compute_derivs == 1
    dA          = dhx;
    dB          = dhu;
    dc          = zeros(x_nbr,totparam_nbr);
    dC          = dgx;
    dD          = dgu;
    dd          = zeros(y_nbr,totparam_nbr);
    dVarinov    = dE_uu;
    dE_xf       = zeros(x_nbr,totparam_nbr);
    dE_inovzlag1 = zeros(z_nbr,inov_nbr,totparam_nbr);
    dVar_z   = zeros(z_nbr,z_nbr,totparam_nbr);
    lyapunov_symm_method = 2;%to spare a lot of computing time while not repeating Schur every time
    for jp1 = 1:totparam_nbr
        if jp1 <= stderrparam_nbr+corrparam_nbr
            dOm_z_jp1 = B*dVarinov(:,:,jp1)*B';
            dVar_z(:,:,jp1) = lyapunov_symm(A, dOm_z_jp1,...
                                           options.lyapunov_fixed_point_tol,options.qz_criterium,options.lyapunov_complex_threshold,...
                                           lyapunov_symm_method,...
                                           options.debug);
        else
            dOm_z_jp1  = dB(:,:,jp1)*Varinov*B' + B*Varinov*dB(:,:,jp1)';
            dVar_z(:,:,jp1) = lyapunov_symm(A, dA(:,:,jp1)*Var_z*A' + A*Var_z*dA(:,:,jp1)' + dOm_z_jp1,...
                                           options.lyapunov_fixed_point_tol,options.qz_criterium,options.lyapunov_complex_threshold,...
                                           lyapunov_symm_method,...
                                           options.debug);
        end
    end
end

if order > 1
    options.qz_criterium = 1; %pruned state space has no unit roots
    % Some common and useful objects for order > 1
    E_xfxf   = Var_z;
    if compute_derivs
        dE_xfxf = dVar_z;
    end
    hx_hx    = kron(hx,hx);
    hx_hu    = kron(hx,hu);
    hu_hu    = kron(hu,hu);
    I_xx     = eye(x_nbr^2);
    K_x_x    = commutation(x_nbr,x_nbr,1);
    invIx_hx = (eye(x_nbr)-hx)\eye(x_nbr);

    %Compute unique fourth order product moments of u, i.e. unique(E[kron(kron(kron(u,u),u),u)],'stable')
    u_nbr4    = u_nbr*(u_nbr+1)/2*(u_nbr+2)/3*(u_nbr+3)/4;
    QPu       = quadruplication(u_nbr);
    COMBOS4   = flipud(allVL1(u_nbr, 4)); %all possible (unique) combinations of powers that sum up to four
    E_u_u_u_u = zeros(u_nbr4,1); %only unique entries
    if compute_derivs && (stderrparam_nbr+corrparam_nbr>0)
        dE_u_u_u_u = zeros(u_nbr4,stderrparam_nbr+corrparam_nbr);
    end
    for j4 = 1:size(COMBOS4,1)
        if compute_derivs && (stderrparam_nbr+corrparam_nbr>0)
            [E_u_u_u_u(j4), dE_u_u_u_u(j4,:)] = prodmom_deriv(E_uu, 1:u_nbr, COMBOS4(j4,:), dE_uu(:,:,1:(stderrparam_nbr+corrparam_nbr)), dr.derivs.dCorrelation_matrix(:,:,1:(stderrparam_nbr+corrparam_nbr)));
        else
            E_u_u_u_u(j4) = prodmom(E_uu, 1:u_nbr, COMBOS4(j4,:));
        end
    end
    E_xfxf_uu = kron(E_xfxf,E_uu');

%% Second-order pruned state space system
% Auxiliary state vector z is defined by:          z    = [xf;xs;kron(xf,xf)]
% Auxiliary innovations vector inov is defined by: inov = [u;kron(u,u)-E_uu(:);kron(xf,u)]
    z_nbr    = x_nbr + x_nbr + x_nbr^2;
    inov_nbr = u_nbr + u_nbr^2 + x_nbr*u_nbr;

    A = zeros(z_nbr, z_nbr);
    A(id_z1_xf    , id_z1_xf   ) = hx;
    A(id_z2_xs    , id_z2_xs   ) = hx;
    A(id_z2_xs    , id_z3_xf_xf) = 1/2*hxx;
    A(id_z3_xf_xf , id_z3_xf_xf) = hx_hx;

    B = zeros(z_nbr, inov_nbr);
    B(id_z1_xf    , id_inov1_u   ) = hu;
    B(id_z2_xs    , id_inov2_u_u ) = 1/2*huu;
    B(id_z2_xs    , id_inov3_xf_u) = hxu;
    B(id_z3_xf_xf , id_inov2_u_u ) = hu_hu;
    B(id_z3_xf_xf , id_inov3_xf_u) = (I_xx+K_x_x)*hx_hu;

    c = zeros(z_nbr, 1);
    c(id_z2_xs    , 1) = 1/2*hss + 1/2*huu*E_uu(:);
    c(id_z3_xf_xf , 1) = hu_hu*E_uu(:);

    C = zeros(y_nbr, z_nbr);
    C(: , id_z1_xf   ) = gx;
    C(: , id_z2_xs   ) = gx;
    C(: , id_z3_xf_xf) = 1/2*gxx;

    D = zeros(y_nbr, inov_nbr);
    D(: , id_inov1_u   ) = gu;
    D(: , id_inov2_u_u ) = 1/2*guu;
    D(: , id_inov3_xf_u) = gxu;

    d = 1/2*gss + 1/2*guu*E_uu(:);

    Varinov = zeros(inov_nbr,inov_nbr);
    Varinov(id_inov1_u    , id_inov1_u)    = E_uu;
   %Varinov(id_inov1_u    , id_inov2_u_u ) = zeros(u_nbr,u_nbr^2);
   %Varinov(id_inov1_u    , id_inov3_xf_u) = zeros(u_nbr,x_nbr*u_nbr);
   %Varinov(id_inov2_u_u  , id_inov1_u   ) = zeros(u_nbr^2,u_nbr);
    Varinov(id_inov2_u_u  , id_inov2_u_u ) = reshape(QPu*E_u_u_u_u,u_nbr^2,u_nbr^2)-E_uu(:)*E_uu(:)';
   %Varinov(id_inov2_u_u  , id_inov3_xf_u) = zeros(u_nbr^2,x_nbr*u_nbr);
   %Varinov(id_inov3_xf_u , id_inov1_u   ) = zeros(x_nbr*u_nbr,u_nbr);
   %Varinov(id_inov3_xf_u , id_inov2_u_u ) = zeros(x_nbr*u_nbr,u_nbr^2);
    Varinov(id_inov3_xf_u , id_inov3_xf_u) = E_xfxf_uu;

    E_xs        = invIx_hx*(1/2*hxx*E_xfxf(:) + c(id_z2_xs,1));
    E_inovzlag1 = zeros(inov_nbr,z_nbr); %at second-order E[z(-1)*inov'] = 0
    Om_z        = B*Varinov*transpose(B);

    lyapunov_symm_method = 1; %method=1 to initialize persistent variables (if errorflag)
    [Var_z, errorflag] = disclyap_fast(A,Om_z,options.lyapunov_doubling_tol);
    if errorflag %use Schur-based method
        fprintf('PRUNED_STATE_SPACE_SYSTEM: error flag in disclyap_fast at order=2, use lyapunov_symm\n');
        Var_z = lyapunov_symm(A,Om_z,...
                              options.lyapunov_fixed_point_tol,options.qz_criterium,options.lyapunov_complex_threshold,...
                              lyapunov_symm_method,...
                              options.debug);
        lyapunov_symm_method = 2; %in the following we can reuse persistent variables
    end
    % Make sure some stuff is zero due to Gaussianity
    Var_z(id_z1_xf    , id_z2_xs   ) = zeros(x_nbr,x_nbr);
    Var_z(id_z1_xf    , id_z3_xf_xf) = zeros(x_nbr,x_nbr^2);
    Var_z(id_z2_xs    , id_z1_xf   ) = zeros(x_nbr,x_nbr);
    Var_z(id_z3_xf_xf , id_z1_xf   ) = zeros(x_nbr^2,x_nbr);

    if compute_derivs
        dA           = zeros(z_nbr,z_nbr,totparam_nbr);
        dB           = zeros(z_nbr,inov_nbr,totparam_nbr);
        dc           = zeros(z_nbr,totparam_nbr);
        dC           = zeros(y_nbr,z_nbr,totparam_nbr);
        dD           = zeros(y_nbr,inov_nbr,totparam_nbr);
        dd           = zeros(y_nbr,totparam_nbr);
        dVarinov     = zeros(inov_nbr,inov_nbr,totparam_nbr);
        dE_xs        = zeros(x_nbr,totparam_nbr);
        dE_inovzlag1 = zeros(inov_nbr,z_nbr,totparam_nbr);
        dVar_z       = zeros(z_nbr,z_nbr,totparam_nbr);
        
        for jp2 = 1:totparam_nbr
            if jp2 <= (stderrparam_nbr+corrparam_nbr)
                dE_uu_jp2      = dE_uu(:,:,jp2);
                dE_u_u_u_u_jp2 = QPu*dE_u_u_u_u(:,jp2);                
            else
                dE_uu_jp2      = zeros(u_nbr,u_nbr);
                dE_u_u_u_u_jp2 = zeros(u_nbr^4,1);            
            end
            dhx_jp2        = dhx(:,:,jp2);
            dhu_jp2        = dhu(:,:,jp2);
            dhxx_jp2       = dhxx(:,:,jp2);
            dhxu_jp2       = dhxu(:,:,jp2);
            dhuu_jp2       = dhuu(:,:,jp2);
            dhss_jp2       = dhss(:,jp2);            
            dgx_jp2        = dgx(:,:,jp2);
            dgu_jp2        = dgu(:,:,jp2);
            dgxx_jp2       = dgxx(:,:,jp2);
            dgxu_jp2       = dgxu(:,:,jp2);
            dguu_jp2       = dguu(:,:,jp2);
            dgss_jp2       = dgss(:,jp2);
            dhx_hx_jp2     = kron(dhx_jp2,hx) + kron(hx,dhx_jp2);
            dhu_hu_jp2     = kron(dhu_jp2,hu) + kron(hu,dhu_jp2);
            dhx_hu_jp2     = kron(dhx_jp2,hu) + kron(hx,dhu_jp2);
            dE_xfxf_jp2    = dE_xfxf(:,:,jp2);
            dE_xfxf_uu_jp2 = kron(dE_xfxf_jp2,E_uu) + kron(E_xfxf,dE_uu_jp2);

            dA(id_z1_xf    , id_z1_xf    , jp2) = dhx_jp2;
            dA(id_z2_xs    , id_z2_xs    , jp2) = dhx_jp2;
            dA(id_z2_xs    , id_z3_xf_xf , jp2) = 1/2*dhxx_jp2;
            dA(id_z3_xf_xf , id_z3_xf_xf , jp2) = dhx_hx_jp2;

            dB(id_z1_xf    , id_inov1_u    , jp2) = dhu_jp2;
            dB(id_z2_xs    , id_inov2_u_u  , jp2) = 1/2*dhuu_jp2;
            dB(id_z2_xs    , id_inov3_xf_u , jp2) = dhxu_jp2;
            dB(id_z3_xf_xf , id_inov2_u_u  , jp2) = dhu_hu_jp2;
            dB(id_z3_xf_xf , id_inov3_xf_u , jp2) = (I_xx+K_x_x)*dhx_hu_jp2;

            dc(id_z2_xs    , jp2) = 1/2*dhss_jp2 + 1/2*dhuu_jp2*E_uu(:) + 1/2*huu*dE_uu_jp2(:);
            dc(id_z3_xf_xf , jp2) = dhu_hu_jp2*E_uu(:) + hu_hu*dE_uu_jp2(:);

            dC(: , id_z1_xf    , jp2) = dgx_jp2;
            dC(: , id_z2_xs    , jp2) = dgx_jp2;
            dC(: , id_z3_xf_xf , jp2) = 1/2*dgxx_jp2;

            dD(: , id_inov1_u    , jp2) = dgu_jp2;
            dD(: , id_inov2_u_u  , jp2) = 1/2*dguu_jp2;
            dD(: , id_inov3_xf_u , jp2) = dgxu_jp2;

            dd(:,jp2) = 1/2*dgss_jp2 + 1/2*guu*dE_uu_jp2(:) + 1/2*dguu_jp2*E_uu(:);

            dVarinov(id_inov1_u    , id_inov1_u    , jp2) = dE_uu_jp2;
            dVarinov(id_inov2_u_u  , id_inov2_u_u  , jp2) = reshape(dE_u_u_u_u_jp2,u_nbr^2,u_nbr^2) - dE_uu_jp2(:)*E_uu(:)' - E_uu(:)*dE_uu_jp2(:)';
            dVarinov(id_inov3_xf_u , id_inov3_xf_u , jp2) = dE_xfxf_uu_jp2;
            
            dE_xs(:,jp2) = invIx_hx*( dhx_jp2*E_xs + 1/2*dhxx_jp2*E_xfxf(:) + 1/2*hxx*dE_xfxf_jp2(:) + dc(id_z2_xs,jp2) );
            dOm_z_jp2    = dB(:,:,jp2)*Varinov*B' + B*dVarinov(:,:,jp2)*B' + B*Varinov*dB(:,:,jp2)';
            
            [dVar_z(:,:,jp2), errorflag] = disclyap_fast(A, dA(:,:,jp2)*Var_z*A' + A*Var_z*dA(:,:,jp2)' + dOm_z_jp2, options.lyapunov_doubling_tol);
            if errorflag
                dVar_z(:,:,jp2) = lyapunov_symm(A, dA(:,:,jp2)*Var_z*A' + A*Var_z*dA(:,:,jp2)' + dOm_z_jp2,...
                                               options.lyapunov_fixed_point_tol,options.qz_criterium,options.lyapunov_complex_threshold,...
                                               lyapunov_symm_method,...
                                               options.debug);
                if lyapunov_symm_method == 1
                    lyapunov_symm_method = 2; %now we can reuse persistent schur
                end
            end
            % Make sure some stuff is zero due to Gaussianity
            dVar_z(id_z1_xf    , id_z2_xs    , jp2) = zeros(x_nbr,x_nbr);
            dVar_z(id_z1_xf    , id_z3_xf_xf , jp2) = zeros(x_nbr,x_nbr^2);    
            dVar_z(id_z2_xs    , id_z1_xf    , jp2) = zeros(x_nbr,x_nbr);    
            dVar_z(id_z3_xf_xf , id_z1_xf    , jp2) = zeros(x_nbr^2,x_nbr);
        end
    end

    if order > 2
        % Some common and useful objects for order > 2
        K_u_xx   = commutation(u_nbr,x_nbr^2,1);
        K_u_ux   = commutation(u_nbr,u_nbr*x_nbr,1);
        hx_hss2  = kron(hx,1/2*hss);
        hu_hss2  = kron(hu,1/2*hss);
        hx_hxx2  = kron(hx,1/2*hxx);
        hxx2_hu  = kron(1/2*hxx,hu);
        hx_hxu   = kron(hx,hxu);
        hxu_hu   = kron(hxu,hu);
        hx_huu2  = kron(hx,1/2*huu);
        hu_huu2  = kron(hu,1/2*huu);
        hx_hx_hx = kron(hx,hx_hx);
        hx_hx_hu = kron(hx_hx,hu);
        hu_hx_hx = kron(hu,hx_hx);
        hu_hu_hu = kron(hu_hu,hu);
        hx_hu_hu = kron(hx,hu_hu);
        hu_hx_hu = kron(hu,hx_hu);
        invIxx_hx_hx = (eye(x_nbr^2)-hx_hx)\eye(x_nbr^2);

        % Reuse second-order results
       %E_xfxf       = Var_z(id_z1_xf, id_z1_xf      );                        %this is E[xf*xf'], we already have that
       %E_xfxs       = Var_z(id_z1_xf, id_z2_xs      );                        %this is E[xf*xs']=0 due to gaussianity
       %E_xfxf_xf    = Var_z(id_z1_xf, id_z3_xf_xf   );                        %this is E[xf*kron(xf_xf)']=0 due to gaussianity
       %E_xsxf       = Var_z(id_z2_xs, id_z1_xf      );                        %this is E[xs*xf']=0 due to gaussianity
        E_xsxs       = Var_z(id_z2_xs, id_z2_xs      ) + E_xs*transpose(E_xs); %this is E[xs*xs']
        E_xsxf_xf    = Var_z(id_z2_xs, id_z3_xf_xf   ) + E_xs*E_xfxf(:)';      %this is E[xs*kron(xf,xf)']
       %E_xf_xfxf    = Var_z(id_z3_xf_xf, id_z1_xf   );                        %this is E[kron(xf,xf)*xf']=0 due to gaussianity
        E_xf_xfxs    = Var_z(id_z3_xf_xf, id_z2_xs   ) + E_xfxf(:)*E_xs';      %this is E[kron(xf,xf)*xs']
        E_xf_xfxf_xf = Var_z(id_z3_xf_xf, id_z3_xf_xf) + E_xfxf(:)*E_xfxf(:)'; %this is E[kron(xf,xf)*kron(xf,xf)']
        E_xrdxf = reshape(invIxx_hx_hx*vec(...
                                             hxx*reshape( commutation(x_nbr^2,x_nbr,1)*E_xf_xfxs(:), x_nbr^2,x_nbr)*hx'...
                                           + hxu*kron(E_xs,E_uu)*hu'...
                                           + 1/6*hxxx*reshape(E_xf_xfxf_xf,x_nbr^3,x_nbr)*hx'...
                                           + 1/6*huuu*reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr)*hu'...
                                           + 3/6*hxxu*kron(E_xfxf(:),E_uu)*hu'...
                                           + 3/6*hxuu*kron(E_xfxf,E_uu(:))*hx'...
                                           + 3/6*hxss*E_xfxf*hx'...
                                           + 3/6*huss*E_uu*hu'...
                                           ),...
                         x_nbr,x_nbr); %this is E[xrd*xf']
        if compute_derivs
            dE_xsxs       = zeros(x_nbr,x_nbr,totparam_nbr);
            dE_xsxf_xf    = zeros(x_nbr,x_nbr^2,totparam_nbr);
            dE_xf_xfxs    = zeros(x_nbr^2,x_nbr,totparam_nbr);
            dE_xf_xfxf_xf = zeros(x_nbr^2,x_nbr^2,totparam_nbr);
            dE_xrdxf      = zeros(x_nbr,x_nbr,totparam_nbr);
            for jp2 = 1:totparam_nbr
                if jp2 < (stderrparam_nbr+corrparam_nbr)
                    dE_u_u_u_u_jp2 = QPu*dE_u_u_u_u(:,jp2);
                else
                    dE_u_u_u_u_jp2 = zeros(u_nbr^4,1);
                end
                dE_xsxs(:,:,jp2)       = dVar_z(id_z2_xs    , id_z2_xs    , jp2) + dE_xs(:,jp2)*transpose(E_xs) + E_xs*transpose(dE_xs(:,jp2));
                dE_xsxf_xf(:,:,jp2)    = dVar_z(id_z2_xs    , id_z3_xf_xf , jp2) + dE_xs(:,jp2)*E_xfxf(:)' + E_xs*vec(dE_xfxf(:,:,jp2))';
                dE_xf_xfxs(:,:,jp2)    = dVar_z(id_z3_xf_xf , id_z2_xs    , jp2) + vec(dE_xfxf(:,:,jp2))*E_xs' + E_xfxf(:)*dE_xs(:,jp2)';
                dE_xf_xfxf_xf(:,:,jp2) = dVar_z(id_z3_xf_xf , id_z3_xf_xf , jp2) + vec(dE_xfxf(:,:,jp2))*E_xfxf(:)' + E_xfxf(:)*vec(dE_xfxf(:,:,jp2))';
                dE_xrdxf(:,:,jp2) = reshape(invIxx_hx_hx*vec(...
                    dhx(:,:,jp2)*E_xrdxf*hx' + hx*E_xrdxf*dhx(:,:,jp2)'...
                  + dhxx(:,:,jp2)*reshape( commutation(x_nbr^2,x_nbr,1)*E_xf_xfxs(:), x_nbr^2,x_nbr)*hx' + hxx*reshape( commutation(x_nbr^2,x_nbr,1)*vec(dE_xf_xfxs(:,:,jp2)), x_nbr^2,x_nbr)*hx' + hxx*reshape( commutation(x_nbr^2,x_nbr,1)*E_xf_xfxs(:), x_nbr^2,x_nbr)*dhx(:,:,jp2)'...
                  + dhxu(:,:,jp2)*kron(E_xs,E_uu)*hu' + hxu*kron(dE_xs(:,jp2),E_uu)*hu' + hxu*kron(E_xs,dE_uu(:,:,jp2))*hu' + hxu*kron(E_xs,E_uu)*dhu(:,:,jp2)'...
                  + 1/6*dhxxx(:,:,jp2)*reshape(E_xf_xfxf_xf,x_nbr^3,x_nbr)*hx' + 1/6*hxxx*reshape(dE_xf_xfxf_xf(:,:,jp2),x_nbr^3,x_nbr)*hx' + 1/6*hxxx*reshape(E_xf_xfxf_xf,x_nbr^3,x_nbr)*dhx(:,:,jp2)'...
                  + 1/6*dhuuu(:,:,jp2)*reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr)*hu' + 1/6*huuu*reshape(dE_u_u_u_u_jp2,u_nbr^3,u_nbr)*hu' + 1/6*huuu*reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr)*dhu(:,:,jp2)'...
                  + 3/6*dhxxu(:,:,jp2)*kron(E_xfxf(:),E_uu)*hu' + 3/6*hxxu*kron(vec(dE_xfxf(:,:,jp2)),E_uu)*hu' + 3/6*hxxu*kron(E_xfxf(:),dE_uu(:,:,jp2))*hu' + 3/6*hxxu*kron(E_xfxf(:),E_uu)*dhu(:,:,jp2)'...
                  + 3/6*dhxuu(:,:,jp2)*kron(E_xfxf,E_uu(:))*hx' + 3/6*hxuu*kron(dE_xfxf(:,:,jp2),E_uu(:))*hx' + 3/6*hxuu*kron(E_xfxf,vec(dE_uu(:,:,jp2)))*hx' + 3/6*hxuu*kron(E_xfxf,E_uu(:))*dhx(:,:,jp2)'...
                  + 3/6*dhxss(:,:,jp2)*E_xfxf*hx' + 3/6*hxss*dE_xfxf(:,:,jp2)*hx' + 3/6*hxss*E_xfxf*dhx(:,:,jp2)'...
                  + 3/6*dhuss(:,:,jp2)*E_uu*hu' + 3/6*huss*dE_uu(:,:,jp2)*hu' + 3/6*huss*E_uu*dhu(:,:,jp2)'...
                  ), x_nbr, x_nbr);
            end
        end

        % Compute unique sixth-order product moments of u, i.e. unique(E[kron(kron(kron(kron(kron(u,u),u),u),u),u)],'stable')
        u_nbr6        = u_nbr*(u_nbr+1)/2*(u_nbr+2)/3*(u_nbr+3)/4*(u_nbr+4)/5*(u_nbr+5)/6;
        Q6Pu          = Q6_plication(u_nbr);
        COMBOS6       = flipud(allVL1(u_nbr, 6)); %all possible (unique) combinations of powers that sum up to six
        E_u_u_u_u_u_u = zeros(u_nbr6,1); %only unique entries
        if compute_derivs && (stderrparam_nbr+corrparam_nbr>0)
            dE_u_u_u_u_u_u = zeros(u_nbr6,stderrparam_nbr+corrparam_nbr);
        end
        for j6 = 1:size(COMBOS6,1)
            if compute_derivs && (stderrparam_nbr+corrparam_nbr>0)
                [E_u_u_u_u_u_u(j6), dE_u_u_u_u_u_u(j6,:)] = prodmom_deriv(E_uu, 1:u_nbr, COMBOS6(j6,:), dE_uu(:,:,1:(stderrparam_nbr+corrparam_nbr)), dr.derivs.dCorrelation_matrix(:,:,1:(stderrparam_nbr+corrparam_nbr)));
            else
                E_u_u_u_u_u_u(j6) = prodmom(E_uu, 1:u_nbr, COMBOS6(j6,:));
            end
        end

%% Third-order pruned state space system
% Auxiliary state vector z is defined by:          z    = [xf; xs; kron(xf,xf); xrd; kron(xf,xs); kron(kron(xf,xf),xf)]
% Auxiliary innovations vector inov is defined by: inov = [u; kron(u,u)-E_uu(:); kron(xf,u); kron(xs,u); kron(kron(xf,xf),u); kron(kron(xf,u),u); kron(kron(u,u),u))]
        z_nbr    = x_nbr + x_nbr + x_nbr^2 + x_nbr + x_nbr^2 + x_nbr^3;
        inov_nbr = u_nbr + u_nbr^2 + x_nbr*u_nbr + x_nbr*u_nbr + x_nbr^2*u_nbr + x_nbr*u_nbr^2 + u_nbr^3;

        A = zeros(z_nbr,z_nbr);
        A(id_z1_xf       , id_z1_xf      ) = hx;
        A(id_z2_xs       , id_z2_xs      ) = hx;
        A(id_z2_xs       , id_z3_xf_xf   ) = 1/2*hxx;
        A(id_z3_xf_xf    , id_z3_xf_xf   ) = hx_hx;
        A(id_z4_xrd      , id_z1_xf      ) = 3/6*hxss;
        A(id_z4_xrd      , id_z4_xrd     ) = hx;
        A(id_z4_xrd      , id_z5_xf_xs   ) = hxx;
        A(id_z4_xrd      , id_z6_xf_xf_xf) = 1/6*hxxx;
        A(id_z5_xf_xs    , id_z1_xf      ) = hx_hss2;
        A(id_z5_xf_xs    , id_z5_xf_xs   ) = hx_hx;
        A(id_z5_xf_xs    , id_z6_xf_xf_xf) = hx_hxx2;
        A(id_z6_xf_xf_xf , id_z6_xf_xf_xf) = hx_hx_hx;

        B = zeros(z_nbr,inov_nbr);
        B(id_z1_xf       , id_inov1_u      ) = hu;
        B(id_z2_xs       , id_inov2_u_u    ) = 1/2*huu;
        B(id_z2_xs       , id_inov3_xf_u   ) = hxu;
        B(id_z3_xf_xf    , id_inov2_u_u    ) = hu_hu;
        B(id_z3_xf_xf    , id_inov3_xf_u   ) = (I_xx+K_x_x)*hx_hu;
        B(id_z4_xrd      , id_inov1_u      ) = 3/6*huss;
        B(id_z4_xrd      , id_inov4_xs_u   ) = hxu;
        B(id_z4_xrd      , id_inov5_xf_xf_u) = 3/6*hxxu;
        B(id_z4_xrd      , id_inov6_xf_u_u ) = 3/6*hxuu;
        B(id_z4_xrd      , id_inov7_u_u_u  ) = 1/6*huuu;
        B(id_z5_xf_xs    , id_inov1_u      ) = hu_hss2;
        B(id_z5_xf_xs    , id_inov4_xs_u   ) = K_x_x*hx_hu;
        B(id_z5_xf_xs    , id_inov5_xf_xf_u) = hx_hxu + K_x_x*hxx2_hu;
        B(id_z5_xf_xs    , id_inov6_xf_u_u ) = hx_huu2 + K_x_x*hxu_hu;
        B(id_z5_xf_xs    , id_inov7_u_u_u  ) = hu_huu2;
        B(id_z6_xf_xf_xf , id_inov5_xf_xf_u) = hx_hx_hu + kron(hx,K_x_x*hx_hu) + hu_hx_hx*K_u_xx;
        B(id_z6_xf_xf_xf , id_inov6_xf_u_u ) = hx_hu_hu + hu_hx_hu*K_u_ux + kron(hu,K_x_x*hx_hu)*K_u_ux;
        B(id_z6_xf_xf_xf , id_inov7_u_u_u  ) = hu_hu_hu;

        c = zeros(z_nbr, 1);
        c(id_z2_xs    , 1) = 1/2*hss + 1/2*huu*E_uu(:);
        c(id_z3_xf_xf , 1) = hu_hu*E_uu(:);

        C = zeros(y_nbr,z_nbr);
        C(: , id_z1_xf      ) = gx + 3/6*gxss;
        C(: , id_z2_xs      ) = gx;
        C(: , id_z3_xf_xf   ) = 1/2*gxx;
        C(: , id_z4_xrd     ) = gx;
        C(: , id_z5_xf_xs   ) = gxx;
        C(: , id_z6_xf_xf_xf) = 1/6*gxxx;

        D = zeros(y_nbr,inov_nbr);
        D(: , id_inov1_u      ) = gu + 3/6*guss;
        D(: , id_inov2_u_u    ) = 1/2*guu;
        D(: , id_inov3_xf_u   ) = gxu;
        D(: , id_inov4_xs_u   ) = gxu;
        D(: , id_inov5_xf_xf_u) = 3/6*gxxu;
        D(: , id_inov6_xf_u_u)  = 3/6*gxuu;
        D(: , id_inov7_u_u_u )  = 1/6*guuu;

        d = 1/2*gss + 1/2*guu*E_uu(:);

        Varinov = zeros(inov_nbr,inov_nbr);
        Varinov(id_inov1_u       , id_inov1_u      ) = E_uu;
       %Varinov(id_inov1_u       , id_inov2_u_u    ) = zeros(u_nbr,u_nbr^2);
       %Varinov(id_inov1_u       , id_inov3_xf_u   ) = zeros(u_nbr,x_nbr*u_nbr);
        Varinov(id_inov1_u       , id_inov4_xs_u   ) = kron(E_xs',E_uu);
        Varinov(id_inov1_u       , id_inov5_xf_xf_u) = kron(E_xfxf(:)',E_uu);
       %Varinov(id_inov1_u       , id_inov6_xf_u_u ) = zeros(u_nbr,x_nbr*u_nbr^2);
        Varinov(id_inov1_u       , id_inov7_u_u_u  ) = reshape(QPu*E_u_u_u_u,u_nbr,u_nbr^3);

       %Varinov(id_inov2_u_u     , id_inov1_u      ) = zeros(u_nbr^2,u_nbr);
        Varinov(id_inov2_u_u     , id_inov2_u_u    ) = reshape(QPu*E_u_u_u_u,u_nbr^2,u_nbr^2)-E_uu(:)*E_uu(:)';
       %Varinov(id_inov2_u_u     , id_inov3_xf_u   ) = zeros(u_nbr^2,x_nbr*u_nbr);
       %Varinov(id_inov2_u_u     , id_inov4_xs_u   ) = zeros(u_nbr^2,x_nbr*u_nbr);
       %Varinov(id_inov2_u_u     , id_inov5_xf_xf_u) = zeros(u_nbr^2,x_nbr^2,u_nbr);
       %Varinov(id_inov2_u_u     , id_inov6_xf_u_u ) = zeros(u_nbr^2,x_nbr*u_nbr^2);
       %Varinov(id_inov2_u_u     , id_inov7_u_u_u  ) = zeros(u_nbr^2,u_nbr^3);

       %Varinov(id_inov3_xf_u    , id_inov1_u      ) = zeros(x_nbr*u_nbr,u_nbr);
       %Varinov(id_inov3_xf_u    , id_inov2_u_u    ) = zeros(x_nbr*u_nbr,u_nbr^2);
        Varinov(id_inov3_xf_u    , id_inov3_xf_u   ) = E_xfxf_uu;
       %Varinov(id_inov3_xf_u    , id_inov4_xs_u   ) = zeros(x_nbr*u_nbr,x_nbr*u_nbr);
       %Varinov(id_inov3_xf_u    , id_inov5_xf_xf_u) = zeros(x_nbr*u_nbr,x_nbr^2*u_nbr);
       %Varinov(id_inov3_xf_u    , id_inov6_xf_u_u ) = zeros(x_nbr*u_nbr,x_nbr*u_nbr^2);
       %Varinov(id_inov3_xf_u    , id_inov7_u_u_u   ) = zeros(x_nbr*u_nbr,u_nbr^3);

        Varinov(id_inov4_xs_u    , id_inov1_u      ) = kron(E_xs,E_uu);
       %Varinov(id_inov4_xs_u    , id_inov2_u_u    ) = zeros(x_nbr*u_nbr,u_nbr^2);
       %Varinov(id_inov4_xs_u    , id_inov3_xf_u   ) = zeros(x_nbr*u_nbr,x_nbr*u_nbr);
        Varinov(id_inov4_xs_u    , id_inov4_xs_u   ) = kron(E_xsxs,E_uu);
        Varinov(id_inov4_xs_u    , id_inov5_xf_xf_u) = kron(E_xsxf_xf, E_uu);
       %Varinov(id_inov4_xs_u    , id_inov6_xf_u_u ) = zeros(x_nbr*u_nbr,x_nbr*u_nbr^2);
        Varinov(id_inov4_xs_u    , id_inov7_u_u_u  ) = kron(E_xs,reshape(QPu*E_u_u_u_u,u_nbr,u_nbr^3));

        Varinov(id_inov5_xf_xf_u , id_inov1_u      ) = kron(E_xfxf(:),E_uu);
       %Varinov(id_inov5_xf_xf_u , id_inov2_u_u    ) = zeros(x_nbr^2*u_nbr,u_nbr^2);
       %Varinov(id_inov5_xf_xf_u , id_inov3_xf_u   ) = zeros(x_nbr^2*u_nbr,x_nbr*u_nbr);
        Varinov(id_inov5_xf_xf_u , id_inov4_xs_u   ) = kron(E_xf_xfxs,E_uu);
        Varinov(id_inov5_xf_xf_u , id_inov5_xf_xf_u) = kron(E_xf_xfxf_xf,E_uu);
       %Varinov(id_inov5_xf_xf_u , id_inov6_xf_u_u ) = zeros(x_nbr^2*u_nbr,x_nbr*u_nbr^2);
        Varinov(id_inov5_xf_xf_u , id_inov7_u_u_u  ) = kron(E_xfxf(:),reshape(QPu*E_u_u_u_u,u_nbr,u_nbr^3));

       %Varinov(id_inov6_xf_u_u  , id_inov1_u      ) = zeros(x_nbr*u_nbr^2,u_nbr);
       %Varinov(id_inov6_xf_u_u  , id_inov2_u_u    ) = zeros(x_nbr*u_nbr^2,u_nbr^2);
       %Varinov(id_inov6_xf_u_u  , id_inov3_xf_u   ) = zeros(x_nbr*u_nbr^2,x_nbr*u_nbr);
       %Varinov(id_inov6_xf_u_u  , id_inov4_xs_u   ) = zeros(x_nbr*u_nbr^2,x_nbr*u_nbr);
       %Varinov(id_inov6_xf_u_u  , id_inov5_xf_xf_u) = zeros(x_nbr*u_nbr^2,x_nbr^2*u_nbr);
        Varinov(id_inov6_xf_u_u  , id_inov6_xf_u_u ) = kron(E_xfxf,reshape(QPu*E_u_u_u_u,u_nbr^2,u_nbr^2));
       %Varinov(id_inov6_xf_u_u  , id_inov7_u_u_u  ) = zeros(x_nbr*u_nbr^2,u_nbr^3);

        Varinov(id_inov7_u_u_u   , id_inov1_u      ) = reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr);
       %Varinov(id_inov7_u_u_u   , id_inov2_u_u    ) = zeros(u_nbr^3,u_nbr^2);
       %Varinov(id_inov7_u_u_u   , id_inov3_xf_u   ) = zeros(u_nbr^3,x_nbr*u_nbr);
        Varinov(id_inov7_u_u_u   , id_inov4_xs_u   ) = kron(E_xs',reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr));
        Varinov(id_inov7_u_u_u   , id_inov5_xf_xf_u) = kron(transpose(E_xfxf(:)),reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr));
       %Varinov(id_inov7_u_u_u   , id_inov6_xf_u_u ) = zeros(u_nbr^3,x_nbr*u_nbr^2);
        Varinov(id_inov7_u_u_u   , id_inov7_u_u_u  ) = reshape(Q6Pu*E_u_u_u_u_u_u,u_nbr^3,u_nbr^3);

        E_xrd = zeros(x_nbr,1);%due to gaussianity

        E_inovzlag1 = zeros(inov_nbr,z_nbr); % Attention: E[inov*z(-1)'] is not equal to zero for a third-order approximation due to kron(kron(xf(-1),u),u)
        E_inovzlag1(id_inov6_xf_u_u , id_z1_xf       ) = kron(E_xfxf,E_uu(:));
        E_inovzlag1(id_inov6_xf_u_u , id_z4_xrd      ) = kron(E_xrdxf',E_uu(:));
        E_inovzlag1(id_inov6_xf_u_u , id_z5_xf_xs    ) = kron(reshape(commutation(x_nbr^2,x_nbr)*vec(E_xsxf_xf),x_nbr,x_nbr^2),vec(E_uu)) ;
        E_inovzlag1(id_inov6_xf_u_u , id_z6_xf_xf_xf ) = kron(reshape(E_xf_xfxf_xf,x_nbr,x_nbr^3),E_uu(:));

        Binovzlag1A= B*E_inovzlag1*transpose(A);
        Om_z = B*Varinov*transpose(B) + Binovzlag1A + transpose(Binovzlag1A);

        lyapunov_symm_method = 1; %method=1 to initialize persistent variables
        [Var_z, errorflag] = disclyap_fast(A,Om_z,options.lyapunov_doubling_tol);        
        if errorflag %use Schur-based method
            fprintf('PRUNED_STATE_SPACE_SYSTEM: error flag in disclyap_fast at order=3, use lyapunov_symm\n');
            Var_z = lyapunov_symm(A,Om_z,...
                                    options.lyapunov_fixed_point_tol,options.qz_criterium,options.lyapunov_complex_threshold,...
                                    lyapunov_symm_method,...
                                    options.debug);
            lyapunov_symm_method = 2; %we can now make use of persistent variables from shur
        end
        %make sure some stuff is zero due to Gaussianity
        Var_z(id_z1_xf       , id_z2_xs)       = zeros(x_nbr,x_nbr);
        Var_z(id_z1_xf       , id_z3_xf_xf)    = zeros(x_nbr,x_nbr^2);
        Var_z(id_z2_xs       , id_z1_xf)       = zeros(x_nbr,x_nbr);
        Var_z(id_z2_xs       , id_z4_xrd)      = zeros(x_nbr,x_nbr);
        Var_z(id_z2_xs       , id_z5_xf_xs)    = zeros(x_nbr,x_nbr^2);
        Var_z(id_z2_xs       , id_z6_xf_xf_xf) = zeros(x_nbr,x_nbr^3);
        Var_z(id_z3_xf_xf    , id_z1_xf)       = zeros(x_nbr^2,x_nbr);
        Var_z(id_z3_xf_xf    , id_z4_xrd)      = zeros(x_nbr^2,x_nbr);
        Var_z(id_z3_xf_xf    , id_z5_xf_xs)    = zeros(x_nbr^2,x_nbr^2);
        Var_z(id_z3_xf_xf    , id_z6_xf_xf_xf) = zeros(x_nbr^2,x_nbr^3);
        Var_z(id_z4_xrd      , id_z2_xs)       = zeros(x_nbr,x_nbr);
        Var_z(id_z4_xrd      , id_z3_xf_xf)    = zeros(x_nbr,x_nbr^2);
        Var_z(id_z5_xf_xs    , id_z2_xs)       = zeros(x_nbr^2,x_nbr);
        Var_z(id_z5_xf_xs    , id_z3_xf_xf)    = zeros(x_nbr^2,x_nbr^2);
        Var_z(id_z6_xf_xf_xf , id_z2_xs)       = zeros(x_nbr^3,x_nbr);
        Var_z(id_z6_xf_xf_xf , id_z3_xf_xf)    = zeros(x_nbr^3,x_nbr^2);
        
        if compute_derivs
            dA           = zeros(z_nbr,z_nbr,totparam_nbr);
            dB           = zeros(z_nbr,inov_nbr,totparam_nbr);
            dc           = zeros(z_nbr,totparam_nbr);
            dC           = zeros(y_nbr,z_nbr,totparam_nbr);
            dD           = zeros(y_nbr,inov_nbr,totparam_nbr);
            dd           = zeros(y_nbr,totparam_nbr);
            dVarinov     = zeros(inov_nbr,inov_nbr,totparam_nbr);
            dE_xrd       = zeros(x_nbr,totparam_nbr);
            dE_inovzlag1 = zeros(inov_nbr,z_nbr,totparam_nbr);
            dVar_z       = zeros(z_nbr,z_nbr,totparam_nbr);
            
            for jp3 = 1:totparam_nbr
                if jp3 <= (stderrparam_nbr+corrparam_nbr)
                    dE_uu_jp3          = dE_uu(:,:,jp3);
                    dE_u_u_u_u_jp3     = QPu*dE_u_u_u_u(:,jp3);
                    dE_u_u_u_u_u_u_jp3 = Q6Pu*dE_u_u_u_u_u_u(:,jp3);
                else
                    dE_uu_jp3          = zeros(u_nbr,u_nbr);
                    dE_u_u_u_u_jp3     = zeros(u_nbr^4,1);
                    dE_u_u_u_u_u_u_jp3 = zeros(u_nbr^6,1);
                end
                dhx_jp3       = dhx(:,:,jp3);
                dhu_jp3       = dhu(:,:,jp3);
                dhxx_jp3      = dhxx(:,:,jp3);
                dhxu_jp3      = dhxu(:,:,jp3);
                dhuu_jp3      = dhuu(:,:,jp3);
                dhss_jp3      = dhss(:,jp3);
                dhxxx_jp3     = dhxxx(:,:,jp3);
                dhxxu_jp3     = dhxxu(:,:,jp3);
                dhxuu_jp3     = dhxuu(:,:,jp3);
                dhuuu_jp3     = dhuuu(:,:,jp3);
                dhxss_jp3     = dhxss(:,:,jp3);
                dhuss_jp3     = dhuss(:,:,jp3);
                dgx_jp3       = dgx(:,:,jp3);
                dgu_jp3       = dgu(:,:,jp3);
                dgxx_jp3      = dgxx(:,:,jp3);
                dgxu_jp3      = dgxu(:,:,jp3);
                dguu_jp3      = dguu(:,:,jp3);
                dgss_jp3      = dgss(:,jp3);
                dgxxx_jp3     = dgxxx(:,:,jp3);
                dgxxu_jp3     = dgxxu(:,:,jp3);
                dgxuu_jp3     = dgxuu(:,:,jp3);
                dguuu_jp3     = dguuu(:,:,jp3);
                dgxss_jp3     = dgxss(:,:,jp3);
                dguss_jp3     = dguss(:,:,jp3);
                
                dhx_hx_jp3    = kron(dhx_jp3,hx) + kron(hx,dhx_jp3);
                dhx_hu_jp3    = kron(dhx_jp3,hu) + kron(hx,dhu_jp3);                
                dhu_hu_jp3    = kron(dhu_jp3,hu) + kron(hu,dhu_jp3);
                dhx_hss2_jp3  = kron(dhx_jp3,1/2*hss) + kron(hx,1/2*dhss_jp3);
                dhu_hss2_jp3  = kron(dhu_jp3,1/2*hss) + kron(hu,1/2*dhss_jp3);
                dhx_hxx2_jp3  = kron(dhx_jp3,1/2*hxx) + kron(hx,1/2*dhxx_jp3);
                dhxx2_hu_jp3  = kron(1/2*dhxx_jp3,hu) + kron(1/2*hxx,dhu_jp3);
                dhx_hxu_jp3   = kron(dhx_jp3,hxu) + kron(hx,dhxu_jp3);
                dhxu_hu_jp3   = kron(dhxu_jp3,hu) + kron(hxu,dhu_jp3);
                dhx_huu2_jp3  = kron(dhx_jp3,1/2*huu) + kron(hx,1/2*dhuu_jp3);
                dhu_huu2_jp3  = kron(dhu_jp3,1/2*huu) + kron(hu,1/2*dhuu_jp3);
                dhx_hx_hx_jp3 = kron(dhx_jp3,hx_hx) + kron(hx,dhx_hx_jp3);
                dhx_hx_hu_jp3 = kron(dhx_hx_jp3,hu) + kron(hx_hx,dhu_jp3);
                dhu_hx_hx_jp3 = kron(dhu_jp3,hx_hx) + kron(hu,dhx_hx_jp3);
                dhu_hu_hu_jp3 = kron(dhu_hu_jp3,hu) + kron(hu_hu,dhu_jp3);
                dhx_hu_hu_jp3 = kron(dhx_jp3,hu_hu) + kron(hx,dhu_hu_jp3);
                dhu_hx_hu_jp3 = kron(dhu_jp3,hx_hu) + kron(hu,dhx_hu_jp3);

                dE_xs_jp3         = dE_xs(:,jp3);
                dE_xfxf_jp3       = dE_xfxf(:,:,jp3);
                dE_xsxs_jp3       = dE_xsxs(:,:,jp3);
                dE_xsxf_xf_jp3    = dE_xsxf_xf(:,:,jp3);
                dE_xfxf_uu_jp3    = kron(dE_xfxf_jp3,E_uu) + kron(E_xfxf,dE_uu_jp3);
                dE_xf_xfxs_jp3    = dE_xf_xfxs(:,:,jp3);
                dE_xf_xfxf_xf_jp3 = dE_xf_xfxf_xf(:,:,jp3);
                dE_xrdxf_jp3      = dE_xrdxf(:,:,jp3);
                
                dA(id_z1_xf       , id_z1_xf       , jp3) = dhx_jp3;
                dA(id_z2_xs       , id_z2_xs       , jp3) = dhx_jp3;
                dA(id_z2_xs       , id_z3_xf_xf    , jp3) = 1/2*dhxx_jp3;
                dA(id_z3_xf_xf    , id_z3_xf_xf    , jp3) = dhx_hx_jp3;
                dA(id_z4_xrd      , id_z1_xf       , jp3) = 3/6*dhxss_jp3;
                dA(id_z4_xrd      , id_z4_xrd      , jp3) = dhx_jp3;
                dA(id_z4_xrd      , id_z5_xf_xs    , jp3) = dhxx_jp3;
                dA(id_z4_xrd      , id_z6_xf_xf_xf , jp3) = 1/6*dhxxx_jp3;
                dA(id_z5_xf_xs    , id_z1_xf       , jp3) = dhx_hss2_jp3;
                dA(id_z5_xf_xs    , id_z5_xf_xs    , jp3) = dhx_hx_jp3;
                dA(id_z5_xf_xs    , id_z6_xf_xf_xf , jp3) = dhx_hxx2_jp3;
                dA(id_z6_xf_xf_xf , id_z6_xf_xf_xf , jp3) = dhx_hx_hx_jp3;

                dB(id_z1_xf       , id_inov1_u       , jp3) = dhu_jp3;
                dB(id_z2_xs       , id_inov2_u_u     , jp3) = 1/2*dhuu_jp3;
                dB(id_z2_xs       , id_inov3_xf_u    , jp3) = dhxu_jp3;
                dB(id_z3_xf_xf    , id_inov2_u_u     , jp3) = dhu_hu_jp3;
                dB(id_z3_xf_xf    , id_inov3_xf_u    , jp3) = (I_xx+K_x_x)*dhx_hu_jp3;
                dB(id_z4_xrd      , id_inov1_u       , jp3) = 3/6*dhuss_jp3;
                dB(id_z4_xrd      , id_inov4_xs_u    , jp3) = dhxu_jp3;
                dB(id_z4_xrd      , id_inov5_xf_xf_u , jp3) = 3/6*dhxxu_jp3;
                dB(id_z4_xrd      , id_inov6_xf_u_u  , jp3) = 3/6*dhxuu_jp3;
                dB(id_z4_xrd      , id_inov7_u_u_u   , jp3) = 1/6*dhuuu_jp3;
                dB(id_z5_xf_xs    , id_inov1_u       , jp3) = dhu_hss2_jp3;
                dB(id_z5_xf_xs    , id_inov4_xs_u    , jp3) = K_x_x*dhx_hu_jp3;
                dB(id_z5_xf_xs    , id_inov5_xf_xf_u , jp3) = dhx_hxu_jp3 + K_x_x*dhxx2_hu_jp3;
                dB(id_z5_xf_xs    , id_inov6_xf_u_u  , jp3) = dhx_huu2_jp3 + K_x_x*dhxu_hu_jp3;
                dB(id_z5_xf_xs    , id_inov7_u_u_u   , jp3) = dhu_huu2_jp3;
                dB(id_z6_xf_xf_xf , id_inov5_xf_xf_u , jp3) = dhx_hx_hu_jp3 + kron(dhx_jp3,K_x_x*hx_hu) + kron(hx,K_x_x*dhx_hu_jp3) + dhu_hx_hx_jp3*K_u_xx;
                dB(id_z6_xf_xf_xf , id_inov6_xf_u_u  , jp3) = dhx_hu_hu_jp3 + dhu_hx_hu_jp3*K_u_ux + kron(dhu_jp3,K_x_x*hx_hu)*K_u_ux + kron(hu,K_x_x*dhx_hu_jp3)*K_u_ux;
                dB(id_z6_xf_xf_xf , id_inov7_u_u_u   , jp3) = dhu_hu_hu_jp3;

                dc(id_z2_xs    , jp3) = 1/2*dhss_jp3 + 1/2*dhuu_jp3*E_uu(:) + 1/2*huu*dE_uu_jp3(:);
                dc(id_z3_xf_xf , jp3) = dhu_hu_jp3*E_uu(:) + hu_hu*dE_uu_jp3(:);

                dC(: , id_z1_xf       , jp3) = dgx_jp3 + 3/6*dgxss_jp3;
                dC(: , id_z2_xs       , jp3) = dgx_jp3;
                dC(: , id_z3_xf_xf    , jp3) = 1/2*dgxx_jp3;
                dC(: , id_z4_xrd      , jp3) = dgx_jp3;
                dC(: , id_z5_xf_xs    , jp3) = dgxx_jp3;
                dC(: , id_z6_xf_xf_xf , jp3) = 1/6*dgxxx_jp3;

                dD(: , id_inov1_u       , jp3) = dgu_jp3 + 3/6*dguss_jp3;
                dD(: , id_inov2_u_u     , jp3) = 1/2*dguu_jp3;
                dD(: , id_inov3_xf_u    , jp3) = dgxu_jp3;
                dD(: , id_inov4_xs_u    , jp3) = dgxu_jp3;
                dD(: , id_inov5_xf_xf_u , jp3) = 3/6*dgxxu_jp3;
                dD(: , id_inov6_xf_u_u  , jp3) = 3/6*dgxuu_jp3;
                dD(: , id_inov7_u_u_u   , jp3) = 1/6*dguuu_jp3;

                dd(:,jp3) = 1/2*dgss_jp3 + 1/2*dguu_jp3*E_uu(:) + 1/2*guu*dE_uu_jp3(:);

                dVarinov(id_inov1_u       , id_inov1_u       , jp3) = dE_uu_jp3;
                dVarinov(id_inov1_u       , id_inov4_xs_u    , jp3) = kron(dE_xs_jp3',E_uu) + kron(E_xs',dE_uu_jp3);
                dVarinov(id_inov1_u       , id_inov5_xf_xf_u , jp3) = kron(dE_xfxf_jp3(:)',E_uu) + kron(E_xfxf(:)',dE_uu_jp3);
                dVarinov(id_inov1_u       , id_inov7_u_u_u   , jp3) = reshape(dE_u_u_u_u_jp3,u_nbr,u_nbr^3);
                dVarinov(id_inov2_u_u     , id_inov2_u_u     , jp3) = reshape(dE_u_u_u_u_jp3,u_nbr^2,u_nbr^2) - dE_uu_jp3(:)*E_uu(:)' - E_uu(:)*dE_uu_jp3(:)';
                dVarinov(id_inov3_xf_u    , id_inov3_xf_u    , jp3) = dE_xfxf_uu_jp3;
                dVarinov(id_inov4_xs_u    , id_inov1_u       , jp3) = kron(dE_xs_jp3,E_uu) + kron(E_xs,dE_uu_jp3);
                dVarinov(id_inov4_xs_u    , id_inov4_xs_u    , jp3) = kron(dE_xsxs_jp3,E_uu) + kron(E_xsxs,dE_uu_jp3);
                dVarinov(id_inov4_xs_u    , id_inov5_xf_xf_u , jp3) = kron(dE_xsxf_xf_jp3, E_uu) + kron(E_xsxf_xf, dE_uu_jp3);
                dVarinov(id_inov4_xs_u    , id_inov7_u_u_u   , jp3) = kron(dE_xs_jp3,reshape(QPu*E_u_u_u_u,u_nbr,u_nbr^3)) + kron(E_xs,reshape(dE_u_u_u_u_jp3,u_nbr,u_nbr^3));
                dVarinov(id_inov5_xf_xf_u , id_inov1_u       , jp3) = kron(dE_xfxf_jp3(:),E_uu) + kron(E_xfxf(:),dE_uu_jp3);
                dVarinov(id_inov5_xf_xf_u , id_inov4_xs_u    , jp3) = kron(dE_xf_xfxs_jp3,E_uu) + kron(E_xf_xfxs,dE_uu_jp3);
                dVarinov(id_inov5_xf_xf_u , id_inov5_xf_xf_u , jp3) = kron(dE_xf_xfxf_xf_jp3,E_uu) + kron(E_xf_xfxf_xf,dE_uu_jp3);
                dVarinov(id_inov5_xf_xf_u , id_inov7_u_u_u   , jp3) = kron(dE_xfxf_jp3(:),reshape(QPu*E_u_u_u_u,u_nbr,u_nbr^3)) + kron(E_xfxf(:),reshape(dE_u_u_u_u_jp3,u_nbr,u_nbr^3));
                dVarinov(id_inov6_xf_u_u  , id_inov6_xf_u_u  , jp3) = kron(dE_xfxf_jp3,reshape(QPu*E_u_u_u_u,u_nbr^2,u_nbr^2)) + kron(E_xfxf,reshape(dE_u_u_u_u_jp3,u_nbr^2,u_nbr^2));
                dVarinov(id_inov7_u_u_u   , id_inov1_u       , jp3) = reshape(dE_u_u_u_u_jp3,u_nbr^3,u_nbr);
                dVarinov(id_inov7_u_u_u   , id_inov4_xs_u    , jp3) = kron(dE_xs_jp3',reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr)) + kron(E_xs',reshape(dE_u_u_u_u_jp3,u_nbr^3,u_nbr));
                dVarinov(id_inov7_u_u_u   , id_inov5_xf_xf_u , jp3) = kron(transpose(dE_xfxf_jp3(:)),reshape(QPu*E_u_u_u_u,u_nbr^3,u_nbr)) + kron(transpose(E_xfxf(:)),reshape(dE_u_u_u_u_jp3,u_nbr^3,u_nbr));
                dVarinov(id_inov7_u_u_u   , id_inov7_u_u_u   , jp3) = reshape(dE_u_u_u_u_u_u_jp3,u_nbr^3,u_nbr^3);

                dE_inovzlag1(id_inov6_xf_u_u , id_z1_xf       , jp3) = kron(dE_xfxf_jp3,E_uu(:)) + kron(E_xfxf,dE_uu_jp3(:));
                dE_inovzlag1(id_inov6_xf_u_u , id_z4_xrd      , jp3) = kron(dE_xrdxf_jp3',E_uu(:)) + kron(E_xrdxf',dE_uu_jp3(:));
                dE_inovzlag1(id_inov6_xf_u_u , id_z5_xf_xs    , jp3) = kron(reshape(commutation(x_nbr^2,x_nbr)*vec(dE_xsxf_xf_jp3),x_nbr,x_nbr^2),vec(E_uu)) + kron(reshape(commutation(x_nbr^2,x_nbr)*vec(E_xsxf_xf),x_nbr,x_nbr^2),vec(dE_uu_jp3)) ;
                dE_inovzlag1(id_inov6_xf_u_u , id_z6_xf_xf_xf , jp3) = kron(reshape(dE_xf_xfxf_xf_jp3,x_nbr,x_nbr^3),E_uu(:)) + kron(reshape(E_xf_xfxf_xf,x_nbr,x_nbr^3),dE_uu_jp3(:));

                dBinovzlag1A_jp3 = dB(:,:,jp3)*E_inovzlag1*transpose(A) + B*dE_inovzlag1(:,:,jp3)*transpose(A) + B*E_inovzlag1*transpose(dA(:,:,jp3));
                dOm_z_jp3 = dB(:,:,jp3)*Varinov*transpose(B) + B*dVarinov(:,:,jp3)*transpose(B) + B*Varinov*transpose(dB(:,:,jp3)) + dBinovzlag1A_jp3 + transpose(dBinovzlag1A_jp3);
                
                [dVar_z(:,:,jp3), errorflag] = disclyap_fast(A, dA(:,:,jp3)*Var_z*A' + A*Var_z*dA(:,:,jp3)' + dOm_z_jp3, options.lyapunov_doubling_tol);
                if errorflag
                    dVar_z(:,:,jp3) = lyapunov_symm(A, dA(:,:,jp3)*Var_z*A' + A*Var_z*dA(:,:,jp3)' + dOm_z_jp3,...
                                                    options.lyapunov_fixed_point_tol,options.qz_criterium,options.lyapunov_complex_threshold,...
                                                    lyapunov_symm_method,...
                                                    options.debug);
                    if lyapunov_symm_method == 1
                        lyapunov_symm_method = 2; %now we can reuse persistent schur
                    end
                end
                %make sure some stuff is zero due to Gaussianity
                dVar_z(id_z1_xf       , id_z2_xs       , jp3) = zeros(x_nbr,x_nbr);
                dVar_z(id_z1_xf       , id_z3_xf_xf    , jp3) = zeros(x_nbr,x_nbr^2);
                dVar_z(id_z2_xs       , id_z1_xf       , jp3) = zeros(x_nbr,x_nbr);
                dVar_z(id_z2_xs       , id_z4_xrd      , jp3) = zeros(x_nbr,x_nbr);
                dVar_z(id_z2_xs       , id_z5_xf_xs    , jp3) = zeros(x_nbr,x_nbr^2);
                dVar_z(id_z2_xs       , id_z6_xf_xf_xf , jp3) = zeros(x_nbr,x_nbr^3);
                dVar_z(id_z3_xf_xf    , id_z1_xf       , jp3) = zeros(x_nbr^2,x_nbr);
                dVar_z(id_z3_xf_xf    , id_z4_xrd      , jp3) = zeros(x_nbr^2,x_nbr);
                dVar_z(id_z3_xf_xf    , id_z5_xf_xs    , jp3) = zeros(x_nbr^2,x_nbr^2);
                dVar_z(id_z3_xf_xf    , id_z6_xf_xf_xf , jp3) = zeros(x_nbr^2,x_nbr^3);
                dVar_z(id_z4_xrd      , id_z2_xs       , jp3) = zeros(x_nbr,x_nbr);
                dVar_z(id_z4_xrd      , id_z3_xf_xf    , jp3) = zeros(x_nbr,x_nbr^2);
                dVar_z(id_z5_xf_xs    , id_z2_xs       , jp3) = zeros(x_nbr^2,x_nbr);
                dVar_z(id_z5_xf_xs    , id_z3_xf_xf    , jp3) = zeros(x_nbr^2,x_nbr^2);
                dVar_z(id_z6_xf_xf_xf , id_z2_xs       , jp3) = zeros(x_nbr^3,x_nbr);
                dVar_z(id_z6_xf_xf_xf , id_z3_xf_xf    , jp3) = zeros(x_nbr^3,x_nbr^2);
            end
        end
    end
end

%% Covariance/Correlation of control variables
Var_y = NaN*ones(y_nbr,y_nbr);
if order < 3
    Var_y(stationary_vars,stationary_vars) = C(stationary_vars,:)*Var_z*C(stationary_vars,:)'...
                                           + D(stationary_vars,:)*Varinov*D(stationary_vars,:)';
else
    Var_y(stationary_vars,stationary_vars) = C(stationary_vars,:)*Var_z*C(stationary_vars,:)'...
                                           + D(stationary_vars,:)*E_inovzlag1*C(stationary_vars,:)'...
                                           + C(stationary_vars,:)*transpose(E_inovzlag1)*D(stationary_vars,:)'...
                                           + D(stationary_vars,:)*Varinov*D(stationary_vars,:)';
end
indzeros = find(abs(Var_y) < 1e-12); %find values that are numerical zero
Var_y(indzeros) = 0;
if useautocorr
    sdy = sqrt(diag(Var_y)); %theoretical standard deviation
    sdy = sdy(stationary_vars);
    sy = sdy*sdy';           %cross products of standard deviations
    Corr_y = NaN*ones(y_nbr,y_nbr);
    Corr_y(stationary_vars,stationary_vars) = Var_y(stationary_vars,stationary_vars)./sy;
    Corr_yi = NaN*ones(y_nbr,y_nbr,nlags);
end

if compute_derivs
    dVar_y = NaN*ones(y_nbr,y_nbr,totparam_nbr);
    if useautocorr
        dCorr_y  = NaN*ones(y_nbr,y_nbr,totparam_nbr);
        dCorr_yi = NaN*ones(y_nbr,y_nbr,nlags,totparam_nbr);
    end
    for jpV=1:totparam_nbr
        if order < 3
            dVar_y_tmp = dC(stationary_vars,:,jpV)*Var_z*C(stationary_vars,:)' + C(stationary_vars,:)*dVar_z(:,:,jpV)*C(stationary_vars,:)' + C(stationary_vars,:)*Var_z*dC(stationary_vars,:,jpV)'...
                                                        + dD(stationary_vars,:,jpV)*Varinov*D(stationary_vars,:)' + D(stationary_vars,:)*dVarinov(:,:,jpV)*D(stationary_vars,:)' + D(stationary_vars,:)*Varinov*dD(stationary_vars,:,jpV)';
        else
            dVar_y_tmp = dC(stationary_vars,:,jpV)*Var_z*C(stationary_vars,:)' + C(stationary_vars,:)*dVar_z(:,:,jpV)*C(stationary_vars,:)' + C(stationary_vars,:)*Var_z*dC(stationary_vars,:,jpV)'...
                                                        + dD(stationary_vars,:,jpV)*E_inovzlag1*C(stationary_vars,:)' + D(stationary_vars,:)*dE_inovzlag1(:,:,jpV)*C(stationary_vars,:)' + D(stationary_vars,:)*E_inovzlag1*dC(stationary_vars,:,jpV)'...
                                                        + dC(stationary_vars,:,jpV)*transpose(E_inovzlag1)*D(stationary_vars,:)' + C(stationary_vars,:)*transpose(dE_inovzlag1(:,:,jpV))*D(stationary_vars,:)' + C(stationary_vars,:)*transpose(E_inovzlag1)*dD(stationary_vars,:,jpV)'...
                                                        + dD(stationary_vars,:,jpV)*Varinov*D(stationary_vars,:)' + D(stationary_vars,:)*dVarinov(:,:,jpV)*D(stationary_vars,:)' + D(stationary_vars,:)*Varinov*dD(stationary_vars,:,jpV)';
        end
        indzeros = find(abs(dVar_y_tmp) < 1e-12); %find values that are numerical zero
        dVar_y_tmp(indzeros) = 0;        
        dVar_y(stationary_vars,stationary_vars,jpV) = dVar_y_tmp;
        if useautocorr
            dsy = 1/2./sdy.*diag(dVar_y(:,:,jpV));
            dsy = dsy(stationary_vars);
            dsy = dsy*sdy'+sdy*dsy';
            dCorr_y(stationary_vars,stationary_vars,jpV) = (dVar_y(stationary_vars,stationary_vars,jpV).*sy-dsy.*Var_y(stationary_vars,stationary_vars))./(sy.*sy);
            dCorr_y(stationary_vars,stationary_vars,jpV) = dCorr_y(stationary_vars,stationary_vars,jpV)-diag(diag(dCorr_y(stationary_vars,stationary_vars,jpV)))+diag(diag(dVar_y(stationary_vars,stationary_vars,jpV)));
        end
    end
end

%% Autocovariances/autocorrelations of lagged control variables
Var_yi = NaN*ones(y_nbr,y_nbr,nlags);
Ai = eye(z_nbr); %this is A^0
hxi = eye(x_nbr);
E_inovzlagi = E_inovzlag1;
Var_zi = Var_z;
if order <= 2
    tmp = A*Var_z*C(stationary_vars,:)' + B*Varinov*D(stationary_vars,:)';
else
    tmp = A*E_inovzlag1'*D(stationary_vars,:)' + B*Varinov*D(stationary_vars,:)';
end
for i = 1:nlags
    if order <= 2
        Var_yi(stationary_vars,stationary_vars,i) = C(stationary_vars,:)*Ai*tmp;
    else
        Var_zi = A*Var_zi + B*E_inovzlagi;
        hxi = hx*hxi;
        E_inovzlagi = zeros(inov_nbr,z_nbr);
        E_inovzlagi(id_inov6_xf_u_u , id_z1_xf       ) = kron(hxi*E_xfxf,E_uu(:));
        E_inovzlagi(id_inov6_xf_u_u , id_z4_xrd      ) = kron(hxi*E_xrdxf',E_uu(:));
        E_inovzlagi(id_inov6_xf_u_u , id_z5_xf_xs    ) = kron(hxi*reshape(commutation(x_nbr^2,x_nbr)*vec(E_xsxf_xf),x_nbr,x_nbr^2),vec(E_uu));
        E_inovzlagi(id_inov6_xf_u_u , id_z6_xf_xf_xf ) = kron(hxi*reshape(E_xf_xfxf_xf,x_nbr,x_nbr^3),E_uu(:));
        Var_yi(stationary_vars,stationary_vars,i)      = C(stationary_vars,:)*Var_zi*C(stationary_vars,:)' + C(stationary_vars,:)*Ai*tmp + D(stationary_vars,:)*E_inovzlagi*C(stationary_vars,:)';
    end    
    if useautocorr
        Corr_yi(stationary_vars,stationary_vars,i) = Var_yi(stationary_vars,stationary_vars,i)./sy;
    end
    Ai = Ai*A; %note that this is A^(i-1)
end

if compute_derivs
    dVar_yi = NaN*ones(y_nbr,y_nbr,nlags,totparam_nbr);
    for jpVi=1:totparam_nbr        
        Ai          = eye(z_nbr);   dAi_jpVi          = zeros(z_nbr,z_nbr);
        hxi         = eye(x_nbr);   dhxi_jpVi         = zeros(x_nbr,x_nbr);
        E_inovzlagi = E_inovzlag1;  dE_inovzlagi_jpVi = dE_inovzlag1(:,:,jpVi);
        Var_zi      = Var_z;        dVar_zi_jpVi      = dVar_z(:,:,jpVi);
        if order <= 2            
            dtmp_jpVi = dA(:,:,jpVi)*Var_z*C(stationary_vars,:)' + A*dVar_z(:,:,jpVi)*C(stationary_vars,:)' + A*Var_z*dC(stationary_vars,:,jpVi)'...
                      + dB(:,:,jpVi)*Varinov*D(stationary_vars,:)' + B*dVarinov(:,:,jpVi)*D(stationary_vars,:)' + B*Varinov*dD(stationary_vars,:,jpVi)';
        else
            dtmp_jpVi = dA(:,:,jpVi)*E_inovzlag1'*D(stationary_vars,:)' + A*dE_inovzlag1(:,:,jpVi)'*D(stationary_vars,:)' + A*E_inovzlag1'*dD(stationary_vars,:,jpVi)'...
                      + dB(:,:,jpVi)*Varinov*D(stationary_vars,:)' + B*dVarinov(:,:,jpVi)*D(stationary_vars,:)' + B*Varinov*dD(stationary_vars,:,jpVi)';
        end

        for i = 1:nlags
            if order <= 2
                dVar_yi(stationary_vars,stationary_vars,i,jpVi) = dC(stationary_vars,:,jpVi)*Ai*tmp + C(stationary_vars,:)*dAi_jpVi*tmp + C(stationary_vars,:)*Ai*dtmp_jpVi;
            else
                Var_zi       = A*Var_zi + B*E_inovzlagi;
                dVar_zi_jpVi = dA(:,:,jpVi)*Var_zi + A*dVar_zi_jpVi + dB(:,:,jpVi)*E_inovzlagi + + B*dE_inovzlagi_jpVi;
                dhxi_jpVi = dhx(:,:,jpVi)*hxi + hx*dhxi_jpVi;
                hxi = hx*hxi;                
                E_inovzlagi = zeros(inov_nbr,z_nbr);
                E_inovzlagi(id_inov6_xf_u_u , id_z1_xf       ) = kron(hxi*E_xfxf,E_uu(:));
                E_inovzlagi(id_inov6_xf_u_u , id_z4_xrd      ) = kron(hxi*E_xrdxf',E_uu(:));
                E_inovzlagi(id_inov6_xf_u_u , id_z5_xf_xs    ) = kron(hxi*reshape(commutation(x_nbr^2,x_nbr)*vec(E_xsxf_xf),x_nbr,x_nbr^2),vec(E_uu));
                E_inovzlagi(id_inov6_xf_u_u , id_z6_xf_xf_xf ) = kron(hxi*reshape(E_xf_xfxf_xf,x_nbr,x_nbr^3),E_uu(:));
                dE_inovzlagi_jpVi = zeros(inov_nbr,z_nbr);
                dE_inovzlagi_jpVi(id_inov6_xf_u_u , id_z1_xf       ) = kron(dhxi_jpVi*E_xfxf,E_uu(:)) + kron(hxi*dE_xfxf(:,:,jpVi),E_uu(:)) + kron(hxi*E_xfxf,vec(dE_uu(:,:,jpVi)));
                dE_inovzlagi_jpVi(id_inov6_xf_u_u , id_z4_xrd      ) = kron(dhxi_jpVi*E_xrdxf',E_uu(:)) + kron(hxi*dE_xrdxf(:,:,jpVi)',E_uu(:)) + kron(hxi*E_xrdxf',vec(dE_uu(:,:,jpVi)));
                dE_inovzlagi_jpVi(id_inov6_xf_u_u , id_z5_xf_xs    ) = kron(dhxi_jpVi*reshape(commutation(x_nbr^2,x_nbr)*vec(E_xsxf_xf),x_nbr,x_nbr^2),vec(E_uu)) + kron(hxi*reshape(commutation(x_nbr^2,x_nbr)*vec(dE_xsxf_xf(:,:,jpVi)),x_nbr,x_nbr^2),vec(E_uu)) + kron(hxi*reshape(commutation(x_nbr^2,x_nbr)*vec(E_xsxf_xf),x_nbr,x_nbr^2),vec(dE_uu(:,:,jpVi)));
                dE_inovzlagi_jpVi(id_inov6_xf_u_u , id_z6_xf_xf_xf ) = kron(dhxi_jpVi*reshape(E_xf_xfxf_xf,x_nbr,x_nbr^3),E_uu(:)) + kron(hxi*reshape(dE_xf_xfxf_xf(:,:,jpVi),x_nbr,x_nbr^3),E_uu(:)) + kron(hxi*reshape(E_xf_xfxf_xf,x_nbr,x_nbr^3),vec(dE_uu(:,:,jpVi)));
                dVar_yi(stationary_vars,stationary_vars,i,jpVi) = dC(stationary_vars,:,jpVi)*Var_zi*C(stationary_vars,:)' + C(stationary_vars,:)*dVar_zi_jpVi*C(stationary_vars,:)' + C(stationary_vars,:)*Var_zi*dC(stationary_vars,:,jpVi)'...
                                                                + dC(stationary_vars,:,jpVi)*Ai*tmp + C(stationary_vars,:)*dAi_jpVi*tmp + C(stationary_vars,:)*Ai*dtmp_jpVi...
                                                                + dD(stationary_vars,:,jpVi)*E_inovzlagi*C(stationary_vars,:)' + D(stationary_vars,:)*dE_inovzlagi_jpVi*C(stationary_vars,:)' + D(stationary_vars,:)*E_inovzlagi*dC(stationary_vars,:,jpVi)';
            end
            if useautocorr
                dsy = 1/2./sdy.*diag(dVar_y(:,:,jpVi));
                dsy = dsy(stationary_vars);
                dsy = dsy*sdy'+sdy*dsy';
                dCorr_yi(stationary_vars,stationary_vars,i,jpVi) = (dVar_yi(stationary_vars,stationary_vars,i,jpVi).*sy-dsy.*Var_yi(stationary_vars,stationary_vars,i))./(sy.*sy);                
            end
            dAi_jpVi = dAi_jpVi*A + Ai*dA(:,:,jpVi);
            Ai = Ai*A;
        end
    end
end    


%% Mean of control variables
E_z = E_xf;
if order > 1
    E_z = [E_xf;E_xs;E_xfxf(:)];
end
if order > 2
    E_xf_xs = zeros(x_nbr^2,1);
    E_xf_xf_xf = zeros(x_nbr^3,1);
    E_z = [E_xf;E_xs;E_xfxf(:);E_xrd;E_xf_xs;E_xf_xf_xf];
end
E_y  = Yss(indy,:) + C*E_z + d;

if compute_derivs
    dE_y = zeros(y_nbr,totparam_nbr);
    for jpE = 1:totparam_nbr
        if order == 1
            dE_z_jpE = dE_xf(:,jpE);
        elseif order == 2
            dE_z_jpE = [dE_xf(:,jpE);dE_xs(:,jpE);vec(dE_xfxf(:,:,jpE))];
        elseif order == 3
            dE_xf_xs_jpE    = zeros(x_nbr^2,1);
            dE_xf_xf_xf_jpE = zeros(x_nbr^3,1);
            dE_z_jpE        = [dE_xf(:,jpE);dE_xs(:,jpE);vec(dE_xfxf(:,:,jpE)); dE_xrd(:,jpE); dE_xf_xs_jpE; dE_xf_xf_xf_jpE];
        end
        dE_y(:,jpE) = dC(:,:,jpE)*E_z + C*dE_z_jpE + dd(:,jpE);
        if jpE > (stderrparam_nbr+corrparam_nbr)
            dE_y(:,jpE) = dE_y(:,jpE) + dYss(indy,jpE-stderrparam_nbr-corrparam_nbr); %add steady state
        end
    end
end
non_stationary_vars = setdiff(1:y_nbr,stationary_vars);
E_y(non_stationary_vars) = NaN;
if compute_derivs
    dE_y(non_stationary_vars,:) = NaN;
end

%% Store into output structure
pruned_state_space.indx = indx;
pruned_state_space.indy = indy;
pruned_state_space.A = A;
pruned_state_space.B = B;
pruned_state_space.C = C;
pruned_state_space.D = D;
pruned_state_space.c = c;
pruned_state_space.d = d;
pruned_state_space.Varinov = Varinov;
pruned_state_space.Var_z  = Var_z; %remove in future [@wmutschl]
pruned_state_space.Var_y  = Var_y;
pruned_state_space.Var_yi = Var_yi;
if useautocorr
    pruned_state_space.Corr_y  = Corr_y;
    pruned_state_space.Corr_yi = Corr_yi;
end
pruned_state_space.E_y = E_y;

if compute_derivs == 1
    pruned_state_space.dA = dA;
    pruned_state_space.dB = dB;
    pruned_state_space.dC = dC;
    pruned_state_space.dD = dD;
    pruned_state_space.dc = dc;
    pruned_state_space.dd = dd;
    pruned_state_space.dVarinov = dVarinov;
    pruned_state_space.dVar_y   = dVar_y;
    pruned_state_space.dVar_yi  = dVar_yi;
    if useautocorr
        pruned_state_space.dCorr_y  = dCorr_y;
        pruned_state_space.dCorr_yi = dCorr_yi;
    end
    pruned_state_space.dE_y = dE_y;
end