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*DECK RADBG
SUBROUTINE RADBG (IDO, IP, L1, IDL1, CC, C1, C2, CH, CH2, WA)
C***BEGIN PROLOGUE RADBG
C***SUBSIDIARY
C***PURPOSE Calculate the fast Fourier transform of subvectors of
C arbitrary length.
C***LIBRARY SLATEC (FFTPACK)
C***TYPE SINGLE PRECISION (RADBG-S)
C***AUTHOR Swarztrauber, P. N., (NCAR)
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 790601 DATE WRITTEN
C 830401 Modified to use SLATEC library source file format.
C 860115 Modified by Ron Boisvert to adhere to Fortran 77 by
C (a) changing dummy array size declarations (1) to (*),
C (b) changing references to intrinsic function FLOAT
C to REAL, and
C (c) changing definition of variable TPI by using
C FORTRAN intrinsic function ATAN instead of a DATA
C statement.
C 881128 Modified by Dick Valent to meet prologue standards.
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900402 Added TYPE section. (WRB)
C***END PROLOGUE RADBG
DIMENSION CH(IDO,L1,*), CC(IDO,IP,*), C1(IDO,L1,*),
+ C2(IDL1,*), CH2(IDL1,*), WA(*)
C***FIRST EXECUTABLE STATEMENT RADBG
TPI = 8.*ATAN(1.)
ARG = TPI/IP
DCP = COS(ARG)
DSP = SIN(ARG)
IDP2 = IDO+2
NBD = (IDO-1)/2
IPP2 = IP+2
IPPH = (IP+1)/2
IF (IDO .LT. L1) GO TO 103
DO 102 K=1,L1
DO 101 I=1,IDO
CH(I,K,1) = CC(I,1,K)
101 CONTINUE
102 CONTINUE
GO TO 106
103 DO 105 I=1,IDO
DO 104 K=1,L1
CH(I,K,1) = CC(I,1,K)
104 CONTINUE
105 CONTINUE
106 DO 108 J=2,IPPH
JC = IPP2-J
J2 = J+J
DO 107 K=1,L1
CH(1,K,J) = CC(IDO,J2-2,K)+CC(IDO,J2-2,K)
CH(1,K,JC) = CC(1,J2-1,K)+CC(1,J2-1,K)
107 CONTINUE
108 CONTINUE
IF (IDO .EQ. 1) GO TO 116
IF (NBD .LT. L1) GO TO 112
DO 111 J=2,IPPH
JC = IPP2-J
DO 110 K=1,L1
CDIR$ IVDEP
DO 109 I=3,IDO,2
IC = IDP2-I
CH(I-1,K,J) = CC(I-1,2*J-1,K)+CC(IC-1,2*J-2,K)
CH(I-1,K,JC) = CC(I-1,2*J-1,K)-CC(IC-1,2*J-2,K)
CH(I,K,J) = CC(I,2*J-1,K)-CC(IC,2*J-2,K)
CH(I,K,JC) = CC(I,2*J-1,K)+CC(IC,2*J-2,K)
109 CONTINUE
110 CONTINUE
111 CONTINUE
GO TO 116
112 DO 115 J=2,IPPH
JC = IPP2-J
CDIR$ IVDEP
DO 114 I=3,IDO,2
IC = IDP2-I
DO 113 K=1,L1
CH(I-1,K,J) = CC(I-1,2*J-1,K)+CC(IC-1,2*J-2,K)
CH(I-1,K,JC) = CC(I-1,2*J-1,K)-CC(IC-1,2*J-2,K)
CH(I,K,J) = CC(I,2*J-1,K)-CC(IC,2*J-2,K)
CH(I,K,JC) = CC(I,2*J-1,K)+CC(IC,2*J-2,K)
113 CONTINUE
114 CONTINUE
115 CONTINUE
116 AR1 = 1.
AI1 = 0.
DO 120 L=2,IPPH
LC = IPP2-L
AR1H = DCP*AR1-DSP*AI1
AI1 = DCP*AI1+DSP*AR1
AR1 = AR1H
DO 117 IK=1,IDL1
C2(IK,L) = CH2(IK,1)+AR1*CH2(IK,2)
C2(IK,LC) = AI1*CH2(IK,IP)
117 CONTINUE
DC2 = AR1
DS2 = AI1
AR2 = AR1
AI2 = AI1
DO 119 J=3,IPPH
JC = IPP2-J
AR2H = DC2*AR2-DS2*AI2
AI2 = DC2*AI2+DS2*AR2
AR2 = AR2H
DO 118 IK=1,IDL1
C2(IK,L) = C2(IK,L)+AR2*CH2(IK,J)
C2(IK,LC) = C2(IK,LC)+AI2*CH2(IK,JC)
118 CONTINUE
119 CONTINUE
120 CONTINUE
DO 122 J=2,IPPH
DO 121 IK=1,IDL1
CH2(IK,1) = CH2(IK,1)+CH2(IK,J)
121 CONTINUE
122 CONTINUE
DO 124 J=2,IPPH
JC = IPP2-J
DO 123 K=1,L1
CH(1,K,J) = C1(1,K,J)-C1(1,K,JC)
CH(1,K,JC) = C1(1,K,J)+C1(1,K,JC)
123 CONTINUE
124 CONTINUE
IF (IDO .EQ. 1) GO TO 132
IF (NBD .LT. L1) GO TO 128
DO 127 J=2,IPPH
JC = IPP2-J
DO 126 K=1,L1
CDIR$ IVDEP
DO 125 I=3,IDO,2
CH(I-1,K,J) = C1(I-1,K,J)-C1(I,K,JC)
CH(I-1,K,JC) = C1(I-1,K,J)+C1(I,K,JC)
CH(I,K,J) = C1(I,K,J)+C1(I-1,K,JC)
CH(I,K,JC) = C1(I,K,J)-C1(I-1,K,JC)
125 CONTINUE
126 CONTINUE
127 CONTINUE
GO TO 132
128 DO 131 J=2,IPPH
JC = IPP2-J
DO 130 I=3,IDO,2
DO 129 K=1,L1
CH(I-1,K,J) = C1(I-1,K,J)-C1(I,K,JC)
CH(I-1,K,JC) = C1(I-1,K,J)+C1(I,K,JC)
CH(I,K,J) = C1(I,K,J)+C1(I-1,K,JC)
CH(I,K,JC) = C1(I,K,J)-C1(I-1,K,JC)
129 CONTINUE
130 CONTINUE
131 CONTINUE
132 CONTINUE
IF (IDO .EQ. 1) RETURN
DO 133 IK=1,IDL1
C2(IK,1) = CH2(IK,1)
133 CONTINUE
DO 135 J=2,IP
DO 134 K=1,L1
C1(1,K,J) = CH(1,K,J)
134 CONTINUE
135 CONTINUE
IF (NBD .GT. L1) GO TO 139
IS = -IDO
DO 138 J=2,IP
IS = IS+IDO
IDIJ = IS
DO 137 I=3,IDO,2
IDIJ = IDIJ+2
DO 136 K=1,L1
C1(I-1,K,J) = WA(IDIJ-1)*CH(I-1,K,J)-WA(IDIJ)*CH(I,K,J)
C1(I,K,J) = WA(IDIJ-1)*CH(I,K,J)+WA(IDIJ)*CH(I-1,K,J)
136 CONTINUE
137 CONTINUE
138 CONTINUE
GO TO 143
139 IS = -IDO
DO 142 J=2,IP
IS = IS+IDO
DO 141 K=1,L1
IDIJ = IS
CDIR$ IVDEP
DO 140 I=3,IDO,2
IDIJ = IDIJ+2
C1(I-1,K,J) = WA(IDIJ-1)*CH(I-1,K,J)-WA(IDIJ)*CH(I,K,J)
C1(I,K,J) = WA(IDIJ-1)*CH(I,K,J)+WA(IDIJ)*CH(I-1,K,J)
140 CONTINUE
141 CONTINUE
142 CONTINUE
143 RETURN
END
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