| [2759] | 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: cosqf1.f,v 1.2 2004/06/15 21:14:57 rodney Exp $ |
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| 11 | ! |
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| 12 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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| 13 | |
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| 14 | SUBROUTINE COSQF1 (N,INC,X,WSAVE,WORK,IER) |
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| 15 | DIMENSION X(INC,*) ,WSAVE(*) ,WORK(*) |
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| 16 | IER = 0 |
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| 17 | NS2 = (N+1)/2 |
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| 18 | NP2 = N+2 |
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| 19 | DO 101 K=2,NS2 |
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| 20 | KC = NP2-K |
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| 21 | WORK(K) = X(1,K)+X(1,KC) |
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| 22 | WORK(KC) = X(1,K)-X(1,KC) |
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| 23 | 101 END DO |
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| 24 | MODN = MOD(N,2) |
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| 25 | IF (MODN .NE. 0) GO TO 301 |
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| 26 | WORK(NS2+1) = X(1,NS2+1)+X(1,NS2+1) |
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| 27 | 301 DO 102 K=2,NS2 |
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| 28 | KC = NP2-K |
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| 29 | X(1,K) = WSAVE(K-1)*WORK(KC)+WSAVE(KC-1)*WORK(K) |
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| 30 | X(1,KC) = WSAVE(K-1)*WORK(K) -WSAVE(KC-1)*WORK(KC) |
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| 31 | 102 END DO |
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| 32 | IF (MODN .NE. 0) GO TO 303 |
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| 33 | X(1,NS2+1) = WSAVE(NS2)*WORK(NS2+1) |
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| 34 | 303 LENX = INC*(N-1) + 1 |
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| 35 | LNSV = N + INT(LOG(REAL(N))) + 4 |
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| 36 | LNWK = N |
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| 37 | ! |
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| 38 | CALL RFFT1F(N,INC,X,LENX,WSAVE(N+1),LNSV,WORK,LNWK,IER1) |
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| 39 | IF (IER1 .NE. 0) THEN |
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| 40 | IER = 20 |
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| 41 | CALL XERFFT ('COSQF1',-5) |
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| 42 | GO TO 400 |
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| 43 | ENDIF |
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| 44 | ! |
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| 45 | DO 103 I=3,N,2 |
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| 46 | XIM1 = .5*(X(1,I-1)+X(1,I)) |
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| 47 | X(1,I) = .5*(X(1,I-1)-X(1,I)) |
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| 48 | X(1,I-1) = XIM1 |
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| 49 | 103 END DO |
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| 50 | 400 RETURN |
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| 51 | END |
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