2 SUBROUTINE RADF4 (IDO, L1, CC, CH, WA1, WA2, WA3)
3 C***BEGIN PROLOGUE RADF4
5 C***PURPOSE Calculate the fast Fourier transform of subvectors of
7 C***LIBRARY SLATEC (FFTPACK)
8 C***TYPE SINGLE PRECISION (RADF4-S)
9 C***AUTHOR Swarztrauber, P. N., (NCAR)
10 C***ROUTINES CALLED (NONE)
11 C***REVISION HISTORY (YYMMDD)
13 C 830401 Modified to use SLATEC library source file format.
14 C 860115 Modified by Ron Boisvert to adhere to Fortran 77 by
15 C (a) changing dummy array size declarations (1) to (*).
16 C (b) changing definition of variable HSQT2 by using
17 C FORTRAN intrinsic function SQRT instead of a DATA
19 C 881128 Modified by Dick Valent to meet prologue standards.
20 C 890831 Modified array declarations. (WRB)
21 C 891214 Prologue converted to Version 4.0 format. (BAB)
22 C 900402 Added TYPE section. (WRB)
23 C***END PROLOGUE RADF4
24 DIMENSION CC(IDO,L1,4), CH(IDO,4,*), WA1(*), WA2(*), WA3(*)
25 C***FIRST EXECUTABLE STATEMENT RADF4
28 TR1 = CC(1,K,2)+CC(1,K,4)
29 TR2 = CC(1,K,1)+CC(1,K,3)
32 CH(IDO,2,K) = CC(1,K,1)-CC(1,K,3)
33 CH(1,3,K) = CC(1,K,4)-CC(1,K,2)
35 IF (IDO-2) 107,105,102
37 IF((IDO-1)/2.LT.L1) GO TO 111
42 CR2 = WA1(I-2)*CC(I-1,K,2)+WA1(I-1)*CC(I,K,2)
43 CI2 = WA1(I-2)*CC(I,K,2)-WA1(I-1)*CC(I-1,K,2)
44 CR3 = WA2(I-2)*CC(I-1,K,3)+WA2(I-1)*CC(I,K,3)
45 CI3 = WA2(I-2)*CC(I,K,3)-WA2(I-1)*CC(I-1,K,3)
46 CR4 = WA3(I-2)*CC(I-1,K,4)+WA3(I-1)*CC(I,K,4)
47 CI4 = WA3(I-2)*CC(I,K,4)-WA3(I-1)*CC(I-1,K,4)
57 CH(IC-1,4,K) = TR2-TR1
61 CH(IC-1,2,K) = TR3-TI4
71 CR2 = WA1(I-2)*CC(I-1,K,2)+WA1(I-1)*CC(I,K,2)
72 CI2 = WA1(I-2)*CC(I,K,2)-WA1(I-1)*CC(I-1,K,2)
73 CR3 = WA2(I-2)*CC(I-1,K,3)+WA2(I-1)*CC(I,K,3)
74 CI3 = WA2(I-2)*CC(I,K,3)-WA2(I-1)*CC(I-1,K,3)
75 CR4 = WA3(I-2)*CC(I-1,K,4)+WA3(I-1)*CC(I,K,4)
76 CI4 = WA3(I-2)*CC(I,K,4)-WA3(I-1)*CC(I-1,K,4)
86 CH(IC-1,4,K) = TR2-TR1
90 CH(IC-1,2,K) = TR3-TI4
95 110 IF (MOD(IDO,2) .EQ. 1) RETURN
97 TI1 = -HSQT2*(CC(IDO,K,2)+CC(IDO,K,4))
98 TR1 = HSQT2*(CC(IDO,K,2)-CC(IDO,K,4))
99 CH(IDO,1,K) = TR1+CC(IDO,K,1)
100 CH(IDO,3,K) = CC(IDO,K,1)-TR1
101 CH(1,2,K) = TI1-CC(IDO,K,3)
102 CH(1,4,K) = TI1+CC(IDO,K,3)