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
|
---
:name: dlacn2
:md5sum: cc8a61551ef83735cc8fbda43e5751a3
:category: :subroutine
:arguments:
- n:
:type: integer
:intent: input
- v:
:type: doublereal
:intent: workspace
:dims:
- n
- x:
:type: doublereal
:intent: input/output
:dims:
- n
- isgn:
:type: integer
:intent: workspace
:dims:
- n
- est:
:type: doublereal
:intent: input/output
- kase:
:type: integer
:intent: input/output
- isave:
:type: integer
:intent: input/output
:dims:
- "3"
:substitutions: {}
:fortran_help: " SUBROUTINE DLACN2( N, V, X, ISGN, EST, KASE, ISAVE )\n\n\
* Purpose\n\
* =======\n\
*\n\
* DLACN2 estimates the 1-norm of a square, real matrix A.\n\
* Reverse communication is used for evaluating matrix-vector products.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* N (input) INTEGER\n\
* The order of the matrix. N >= 1.\n\
*\n\
* V (workspace) DOUBLE PRECISION array, dimension (N)\n\
* On the final return, V = A*W, where EST = norm(V)/norm(W)\n\
* (W is not returned).\n\
*\n\
* X (input/output) DOUBLE PRECISION array, dimension (N)\n\
* On an intermediate return, X should be overwritten by\n\
* A * X, if KASE=1,\n\
* A' * X, if KASE=2,\n\
* and DLACN2 must be re-called with all the other parameters\n\
* unchanged.\n\
*\n\
* ISGN (workspace) INTEGER array, dimension (N)\n\
*\n\
* EST (input/output) DOUBLE PRECISION\n\
* On entry with KASE = 1 or 2 and ISAVE(1) = 3, EST should be\n\
* unchanged from the previous call to DLACN2.\n\
* On exit, EST is an estimate (a lower bound) for norm(A). \n\
*\n\
* KASE (input/output) INTEGER\n\
* On the initial call to DLACN2, KASE should be 0.\n\
* On an intermediate return, KASE will be 1 or 2, indicating\n\
* whether X should be overwritten by A * X or A' * X.\n\
* On the final return from DLACN2, KASE will again be 0.\n\
*\n\
* ISAVE (input/output) INTEGER array, dimension (3)\n\
* ISAVE is used to save variables between calls to DLACN2\n\
*\n\n\
* Further Details\n\
* ======= =======\n\
*\n\
* Contributed by Nick Higham, University of Manchester.\n\
* Originally named SONEST, dated March 16, 1988.\n\
*\n\
* Reference: N.J. Higham, \"FORTRAN codes for estimating the one-norm of\n\
* a real or complex matrix, with applications to condition estimation\",\n\
* ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.\n\
*\n\
* This is a thread safe version of DLACON, which uses the array ISAVE\n\
* in place of a SAVE statement, as follows:\n\
*\n\
* DLACON DLACN2\n\
* JUMP ISAVE(1)\n\
* J ISAVE(2)\n\
* ITER ISAVE(3)\n\
*\n\
* =====================================================================\n\
*\n"
|
