| 1 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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| 2 | ! |
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| 3 | ! FFTPACK 5.0 |
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| 4 | ! Copyright (C) 1995-2004, Scientific Computing Division, |
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| 5 | ! University Corporation for Atmospheric Research |
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| 6 | ! Licensed under the GNU General Public License (GPL) |
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| 7 | ! |
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| 8 | ! Authors: Paul N. Swarztrauber and Richard A. Valent |
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| 9 | ! |
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| 10 | ! $Id: mcstb1.f,v 1.2 2004/06/15 21:29:19 rodney Exp $ |
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| 11 | ! |
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| 12 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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| 13 | |
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| 14 | SUBROUTINE MCSTB1(LOT,JUMP,N,INC,X,WSAVE,DSUM,WORK,IER) |
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| 15 | REAL X(INC,*) ,WSAVE(*) |
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| 16 | DOUBLE PRECISION DSUM(*) |
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| 17 | IER = 0 |
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| 18 | NM1 = N-1 |
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| 19 | NP1 = N+1 |
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| 20 | NS2 = N/2 |
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| 21 | LJ = (LOT-1)*JUMP+1 |
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| 22 | IF (N-2) 106,101,102 |
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| 23 | 101 DO 111 M=1,LJ,JUMP |
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| 24 | X1H = X(M,1)+X(M,2) |
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| 25 | X(M,2) = X(M,1)-X(M,2) |
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| 26 | X(M,1) = X1H |
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| 27 | 111 END DO |
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| 28 | RETURN |
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| 29 | 102 IF (N .GT. 3) GO TO 103 |
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| 30 | DO 112 M=1,LJ,JUMP |
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| 31 | X1P3 = X(M,1)+X(M,3) |
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| 32 | X2 = X(M,2) |
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| 33 | X(M,2) = X(M,1)-X(M,3) |
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| 34 | X(M,1) = X1P3+X2 |
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| 35 | X(M,3) = X1P3-X2 |
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| 36 | 112 END DO |
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| 37 | RETURN |
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| 38 | 103 DO 118 M=1,LJ,JUMP |
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| 39 | X(M,1) = X(M,1)+X(M,1) |
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| 40 | X(M,N) = X(M,N)+X(M,N) |
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| 41 | 118 END DO |
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| 42 | M1 = 0 |
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| 43 | DO 113 M=1,LJ,JUMP |
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| 44 | M1 = M1+1 |
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| 45 | DSUM(M1) = X(M,1)-X(M,N) |
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| 46 | X(M,1) = X(M,1)+X(M,N) |
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| 47 | 113 END DO |
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| 48 | DO 104 K=2,NS2 |
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| 49 | M1 = 0 |
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| 50 | DO 114 M=1,LJ,JUMP |
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| 51 | M1 = M1+1 |
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| 52 | KC = NP1-K |
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| 53 | T1 = X(M,K)+X(M,KC) |
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| 54 | T2 = X(M,K)-X(M,KC) |
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| 55 | DSUM(M1) = DSUM(M1)+WSAVE(KC)*T2 |
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| 56 | T2 = WSAVE(K)*T2 |
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| 57 | X(M,K) = T1-T2 |
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| 58 | X(M,KC) = T1+T2 |
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| 59 | 114 CONTINUE |
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| 60 | 104 END DO |
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| 61 | MODN = MOD(N,2) |
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| 62 | IF (MODN .EQ. 0) GO TO 124 |
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| 63 | DO 123 M=1,LJ,JUMP |
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| 64 | X(M,NS2+1) = X(M,NS2+1)+X(M,NS2+1) |
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| 65 | 123 CONTINUE |
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| 66 | 124 CONTINUE |
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| 67 | LENX = (LOT-1)*JUMP + INC*(NM1-1) + 1 |
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| 68 | LNSV = NM1 + INT(LOG(REAL(NM1))) + 4 |
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| 69 | LNWK = LOT*NM1 |
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| 70 | ! |
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| 71 | CALL RFFTMF(LOT,JUMP,NM1,INC,X,LENX,WSAVE(N+1),LNSV,WORK, & |
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| 72 | & LNWK,IER1) |
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| 73 | IF (IER1 .NE. 0) THEN |
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| 74 | IER = 20 |
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| 75 | CALL XERFFT ('MCSTB1',-5) |
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| 76 | GO TO 106 |
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| 77 | ENDIF |
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| 78 | ! |
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| 79 | FNM1S2 = FLOAT(NM1)/2. |
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| 80 | M1 = 0 |
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| 81 | DO 10 M=1,LJ,JUMP |
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| 82 | M1 = M1+1 |
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| 83 | DSUM(M1) = .5*DSUM(M1) |
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| 84 | X(M,1) = FNM1S2*X(M,1) |
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| 85 | 10 END DO |
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| 86 | IF(MOD(NM1,2) .NE. 0) GO TO 30 |
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| 87 | DO 20 M=1,LJ,JUMP |
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| 88 | X(M,NM1) = X(M,NM1)+X(M,NM1) |
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| 89 | 20 END DO |
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| 90 | 30 FNM1S4 = FLOAT(NM1)/4. |
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| 91 | DO 105 I=3,N,2 |
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| 92 | M1 = 0 |
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| 93 | DO 115 M=1,LJ,JUMP |
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| 94 | M1 = M1+1 |
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| 95 | XI = FNM1S4*X(M,I) |
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| 96 | X(M,I) = FNM1S4*X(M,I-1) |
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| 97 | X(M,I-1) = DSUM(M1) |
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| 98 | DSUM(M1) = DSUM(M1)+XI |
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| 99 | 115 END DO |
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| 100 | 105 END DO |
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| 101 | IF (MODN .NE. 0) RETURN |
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| 102 | M1 = 0 |
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| 103 | DO 116 M=1,LJ,JUMP |
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| 104 | M1 = M1+1 |
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| 105 | X(M,N) = DSUM(M1) |
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| 106 | 116 END DO |
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| 107 | 106 CONTINUE |
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| 108 | RETURN |
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| 109 | END |
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