| 1 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
|---|
| 2 | ! |
|---|
| 3 | ! FFTPACK 5.0 |
|---|
| 4 | ! Copyright (C) 1995-2004, Scientific Computing Division, |
|---|
| 5 | ! University Corporation for Atmospheric Research |
|---|
| 6 | ! Licensed under the GNU General Public License (GPL) |
|---|
| 7 | ! |
|---|
| 8 | ! Authors: Paul N. Swarztrauber and Richard A. Valent |
|---|
| 9 | ! |
|---|
| 10 | ! $Id: msntb1.f,v 1.2 2004/06/15 21:29:20 rodney Exp $ |
|---|
| 11 | ! |
|---|
| 12 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
|---|
| 13 | |
|---|
| 14 | SUBROUTINE MSNTB1(LOT,JUMP,N,INC,X,WSAVE,DSUM,XH,WORK,IER) |
|---|
| 15 | REAL X(INC,*) ,WSAVE(*) ,XH(LOT,*) |
|---|
| 16 | DOUBLE PRECISION DSUM(*) |
|---|
| 17 | IER = 0 |
|---|
| 18 | LJ = (LOT-1)*JUMP+1 |
|---|
| 19 | IF (N-2) 200,102,103 |
|---|
| 20 | 102 SRT3S2 = SQRT(3.)/2. |
|---|
| 21 | DO 112 M=1,LJ,JUMP |
|---|
| 22 | XHOLD = SRT3S2*(X(M,1)+X(M,2)) |
|---|
| 23 | X(M,2) = SRT3S2*(X(M,1)-X(M,2)) |
|---|
| 24 | X(M,1) = XHOLD |
|---|
| 25 | 112 END DO |
|---|
| 26 | GO TO 200 |
|---|
| 27 | 103 NP1 = N+1 |
|---|
| 28 | NS2 = N/2 |
|---|
| 29 | DO 104 K=1,NS2 |
|---|
| 30 | KC = NP1-K |
|---|
| 31 | M1 = 0 |
|---|
| 32 | DO 114 M=1,LJ,JUMP |
|---|
| 33 | M1 = M1+1 |
|---|
| 34 | T1 = X(M,K)-X(M,KC) |
|---|
| 35 | T2 = WSAVE(K)*(X(M,K)+X(M,KC)) |
|---|
| 36 | XH(M1,K+1) = T1+T2 |
|---|
| 37 | XH(M1,KC+1) = T2-T1 |
|---|
| 38 | 114 CONTINUE |
|---|
| 39 | 104 END DO |
|---|
| 40 | MODN = MOD(N,2) |
|---|
| 41 | IF (MODN .EQ. 0) GO TO 124 |
|---|
| 42 | M1 = 0 |
|---|
| 43 | DO 123 M=1,LJ,JUMP |
|---|
| 44 | M1 = M1+1 |
|---|
| 45 | XH(M1,NS2+2) = 4.*X(M,NS2+1) |
|---|
| 46 | 123 END DO |
|---|
| 47 | 124 DO 127 M=1,LOT |
|---|
| 48 | XH(M,1) = 0. |
|---|
| 49 | 127 END DO |
|---|
| 50 | LNXH = LOT-1 + LOT*(NP1-1) + 1 |
|---|
| 51 | LNSV = NP1 + INT(LOG(REAL(NP1))) + 4 |
|---|
| 52 | LNWK = LOT*NP1 |
|---|
| 53 | ! |
|---|
| 54 | CALL RFFTMF(LOT,1,NP1,LOT,XH,LNXH,WSAVE(NS2+1),LNSV,WORK, & |
|---|
| 55 | & LNWK,IER1) |
|---|
| 56 | IF (IER1 .NE. 0) THEN |
|---|
| 57 | IER = 20 |
|---|
| 58 | CALL XERFFT ('MSNTB1',-5) |
|---|
| 59 | GO TO 200 |
|---|
| 60 | ENDIF |
|---|
| 61 | ! |
|---|
| 62 | IF(MOD(NP1,2) .NE. 0) GO TO 30 |
|---|
| 63 | DO 20 M=1,LOT |
|---|
| 64 | XH(M,NP1) = XH(M,NP1)+XH(M,NP1) |
|---|
| 65 | 20 END DO |
|---|
| 66 | 30 FNP1S4 = FLOAT(NP1)/4. |
|---|
| 67 | M1 = 0 |
|---|
| 68 | DO 125 M=1,LJ,JUMP |
|---|
| 69 | M1 = M1+1 |
|---|
| 70 | X(M,1) = FNP1S4*XH(M1,1) |
|---|
| 71 | DSUM(M1) = X(M,1) |
|---|
| 72 | 125 END DO |
|---|
| 73 | DO 105 I=3,N,2 |
|---|
| 74 | M1 = 0 |
|---|
| 75 | DO 115 M=1,LJ,JUMP |
|---|
| 76 | M1 = M1+1 |
|---|
| 77 | X(M,I-1) = FNP1S4*XH(M1,I) |
|---|
| 78 | DSUM(M1) = DSUM(M1)+FNP1S4*XH(M1,I-1) |
|---|
| 79 | X(M,I) = DSUM(M1) |
|---|
| 80 | 115 CONTINUE |
|---|
| 81 | 105 END DO |
|---|
| 82 | IF (MODN .NE. 0) GO TO 200 |
|---|
| 83 | M1 = 0 |
|---|
| 84 | DO 116 M=1,LJ,JUMP |
|---|
| 85 | M1 = M1+1 |
|---|
| 86 | X(M,N) = FNP1S4*XH(M1,N+1) |
|---|
| 87 | 116 END DO |
|---|
| 88 | ! |
|---|
| 89 | 200 CONTINUE |
|---|
| 90 | RETURN |
|---|
| 91 | END |
|---|
