| 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: msntf1.f,v 1.2 2004/06/15 21:29:20 rodney Exp $ |
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| 11 | ! |
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| 12 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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| 13 | |
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| 14 | SUBROUTINE MSNTF1(LOT,JUMP,N,INC,X,WSAVE,DSUM,XH,WORK,IER) |
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| 15 | REAL X(INC,*) ,WSAVE(*) ,XH(LOT,*) |
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| 16 | DOUBLE PRECISION DSUM(*) |
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| 17 | IER = 0 |
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| 18 | LJ = (LOT-1)*JUMP+1 |
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| 19 | IF (N-2) 101,102,103 |
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| 20 | 102 SSQRT3 = 1./SQRT(3.) |
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| 21 | DO 112 M=1,LJ,JUMP |
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| 22 | XHOLD = SSQRT3*(X(M,1)+X(M,2)) |
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| 23 | X(M,2) = SSQRT3*(X(M,1)-X(M,2)) |
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| 24 | X(M,1) = XHOLD |
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| 25 | 112 END DO |
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| 26 | 101 GO TO 200 |
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| 27 | 103 NP1 = N+1 |
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| 28 | NS2 = N/2 |
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| 29 | DO 104 K=1,NS2 |
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| 30 | KC = NP1-K |
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| 31 | M1 = 0 |
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| 32 | DO 114 M=1,LJ,JUMP |
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| 33 | M1 = M1 + 1 |
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| 34 | T1 = X(M,K)-X(M,KC) |
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| 35 | T2 = WSAVE(K)*(X(M,K)+X(M,KC)) |
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| 36 | XH(M1,K+1) = T1+T2 |
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| 37 | XH(M1,KC+1) = T2-T1 |
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| 38 | 114 CONTINUE |
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| 39 | 104 END DO |
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| 40 | MODN = MOD(N,2) |
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| 41 | IF (MODN .EQ. 0) GO TO 124 |
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| 42 | M1 = 0 |
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| 43 | DO 123 M=1,LJ,JUMP |
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| 44 | M1 = M1 + 1 |
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| 45 | XH(M1,NS2+2) = 4.*X(M,NS2+1) |
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| 46 | 123 END DO |
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| 47 | 124 DO 127 M=1,LOT |
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| 48 | XH(M,1) = 0. |
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| 49 | 127 END DO |
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| 50 | LNXH = LOT-1 + LOT*(NP1-1) + 1 |
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| 51 | LNSV = NP1 + INT(LOG(REAL(NP1))) + 4 |
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| 52 | LNWK = LOT*NP1 |
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| 53 | ! |
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| 54 | CALL RFFTMF(LOT,1,NP1,LOT,XH,LNXH,WSAVE(NS2+1),LNSV,WORK, & |
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| 55 | & LNWK,IER1) |
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| 56 | IF (IER1 .NE. 0) THEN |
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| 57 | IER = 20 |
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| 58 | CALL XERFFT ('MSNTF1',-5) |
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| 59 | GO TO 200 |
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| 60 | ENDIF |
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| 61 | ! |
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| 62 | IF(MOD(NP1,2) .NE. 0) GO TO 30 |
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| 63 | DO 20 M=1,LOT |
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| 64 | XH(M,NP1) = XH(M,NP1)+XH(M,NP1) |
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| 65 | 20 END DO |
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| 66 | 30 SFNP1 = 1./FLOAT(NP1) |
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| 67 | M1 = 0 |
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| 68 | DO 125 M=1,LJ,JUMP |
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| 69 | M1 = M1+1 |
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| 70 | X(M,1) = .5*XH(M1,1) |
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| 71 | DSUM(M1) = X(M,1) |
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| 72 | 125 END DO |
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| 73 | DO 105 I=3,N,2 |
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| 74 | M1 = 0 |
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| 75 | DO 115 M=1,LJ,JUMP |
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| 76 | M1 = M1+1 |
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| 77 | X(M,I-1) = .5*XH(M1,I) |
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| 78 | DSUM(M1) = DSUM(M1)+.5*XH(M1,I-1) |
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| 79 | X(M,I) = DSUM(M1) |
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| 80 | 115 CONTINUE |
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| 81 | 105 END DO |
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| 82 | IF (MODN .NE. 0) GO TO 200 |
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| 83 | M1 = 0 |
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| 84 | DO 116 M=1,LJ,JUMP |
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| 85 | M1 = M1+1 |
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| 86 | X(M,N) = .5*XH(M1,N+1) |
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| 87 | 116 END DO |
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| 88 | 200 CONTINUE |
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| 89 | RETURN |
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| 90 | END |
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