| 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: rfftf1.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 RFFTF1 (N,IN,C,CH,WA,FAC) |
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| 15 | REAL CH(*) ,C(IN,*) ,WA(N) ,FAC(15) |
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| 16 | ! |
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| 17 | NF = FAC(2) |
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| 18 | NA = 1 |
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| 19 | L2 = N |
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| 20 | IW = N |
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| 21 | DO 111 K1=1,NF |
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| 22 | KH = NF-K1 |
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| 23 | IP = FAC(KH+3) |
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| 24 | L1 = L2/IP |
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| 25 | IDO = N/L2 |
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| 26 | IDL1 = IDO*L1 |
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| 27 | IW = IW-(IP-1)*IDO |
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| 28 | NA = 1-NA |
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| 29 | IF (IP .NE. 4) GO TO 102 |
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| 30 | IX2 = IW+IDO |
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| 31 | IX3 = IX2+IDO |
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| 32 | IF (NA .NE. 0) GO TO 101 |
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| 33 | CALL R1F4KF (IDO,L1,C,IN,CH,1,WA(IW),WA(IX2),WA(IX3)) |
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| 34 | GO TO 110 |
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| 35 | 101 CALL R1F4KF (IDO,L1,CH,1,C,IN,WA(IW),WA(IX2),WA(IX3)) |
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| 36 | GO TO 110 |
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| 37 | 102 IF (IP .NE. 2) GO TO 104 |
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| 38 | IF (NA .NE. 0) GO TO 103 |
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| 39 | CALL R1F2KF (IDO,L1,C,IN,CH,1,WA(IW)) |
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| 40 | GO TO 110 |
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| 41 | 103 CALL R1F2KF (IDO,L1,CH,1,C,IN,WA(IW)) |
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| 42 | GO TO 110 |
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| 43 | 104 IF (IP .NE. 3) GO TO 106 |
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| 44 | IX2 = IW+IDO |
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| 45 | IF (NA .NE. 0) GO TO 105 |
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| 46 | CALL R1F3KF (IDO,L1,C,IN,CH,1,WA(IW),WA(IX2)) |
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| 47 | GO TO 110 |
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| 48 | 105 CALL R1F3KF (IDO,L1,CH,1,C,IN,WA(IW),WA(IX2)) |
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| 49 | GO TO 110 |
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| 50 | 106 IF (IP .NE. 5) GO TO 108 |
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| 51 | IX2 = IW+IDO |
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| 52 | IX3 = IX2+IDO |
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| 53 | IX4 = IX3+IDO |
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| 54 | IF (NA .NE. 0) GO TO 107 |
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| 55 | CALL R1F5KF (IDO,L1,C,IN,CH,1,WA(IW),WA(IX2), & |
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| 56 | & WA(IX3),WA(IX4)) |
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| 57 | GO TO 110 |
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| 58 | 107 CALL R1F5KF (IDO,L1,CH,1,C,IN,WA(IW),WA(IX2), & |
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| 59 | & WA(IX3),WA(IX4)) |
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| 60 | GO TO 110 |
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| 61 | 108 IF (IDO .EQ. 1) NA = 1-NA |
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| 62 | IF (NA .NE. 0) GO TO 109 |
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| 63 | CALL R1FGKF (IDO,IP,L1,IDL1,C,C,C,IN,CH,CH,1,WA(IW)) |
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| 64 | NA = 1 |
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| 65 | GO TO 110 |
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| 66 | 109 CALL R1FGKF (IDO,IP,L1,IDL1,CH,CH,CH,1,C,C,IN,WA(IW)) |
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| 67 | NA = 0 |
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| 68 | 110 L2 = L1 |
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| 69 | 111 END DO |
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| 70 | SN = 1./N |
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| 71 | TSN = 2./N |
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| 72 | TSNM = -TSN |
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| 73 | MODN = MOD(N,2) |
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| 74 | NL = N-2 |
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| 75 | IF(MODN .NE. 0) NL = N-1 |
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| 76 | IF (NA .NE. 0) GO TO 120 |
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| 77 | C(1,1) = SN*CH(1) |
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| 78 | DO 118 J=2,NL,2 |
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| 79 | C(1,J) = TSN*CH(J) |
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| 80 | C(1,J+1) = TSNM*CH(J+1) |
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| 81 | 118 END DO |
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| 82 | IF(MODN .NE. 0) RETURN |
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| 83 | C(1,N) = SN*CH(N) |
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| 84 | RETURN |
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| 85 | 120 C(1,1) = SN*C(1,1) |
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| 86 | DO 122 J=2,NL,2 |
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| 87 | C(1,J) = TSN*C(1,J) |
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| 88 | C(1,J+1) = TSNM*C(1,J+1) |
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| 89 | 122 END DO |
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| 90 | IF(MODN .NE. 0) RETURN |
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| 91 | C(1,N) = SN*C(1,N) |
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| 92 | RETURN |
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| 93 | END |
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