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Last change
on this file since 2759 was
2759,
checked in by aslmd, 2 years ago
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adding unmodified code from WRFV3.0.1.1, expurged from useless data +1M size
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File size:
2.4 KB
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| 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: rffti1.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 RFFTI1 (N,WA,FAC) |
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| 15 | REAL WA(N) ,FAC(15) |
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| 16 | INTEGER NTRYH(4) |
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| 17 | DOUBLE PRECISION TPI,ARGH,ARGLD,ARG |
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| 18 | DATA NTRYH(1),NTRYH(2),NTRYH(3),NTRYH(4)/4,2,3,5/ |
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| 19 | ! |
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| 20 | NL = N |
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| 21 | NF = 0 |
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| 22 | J = 0 |
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| 23 | 101 J = J+1 |
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| 24 | IF (J-4) 102,102,103 |
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| 25 | 102 NTRY = NTRYH(J) |
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| 26 | GO TO 104 |
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| 27 | 103 NTRY = NTRY+2 |
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| 28 | 104 NQ = NL/NTRY |
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| 29 | NR = NL-NTRY*NQ |
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| 30 | IF (NR) 101,105,101 |
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| 31 | 105 NF = NF+1 |
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| 32 | FAC(NF+2) = NTRY |
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| 33 | NL = NQ |
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| 34 | IF (NTRY .NE. 2) GO TO 107 |
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| 35 | IF (NF .EQ. 1) GO TO 107 |
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| 36 | DO 106 I=2,NF |
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| 37 | IB = NF-I+2 |
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| 38 | FAC(IB+2) = FAC(IB+1) |
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| 39 | 106 END DO |
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| 40 | FAC(3) = 2 |
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| 41 | 107 IF (NL .NE. 1) GO TO 104 |
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| 42 | FAC(1) = N |
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| 43 | FAC(2) = NF |
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| 44 | TPI = 8.D0*DATAN(1.D0) |
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| 45 | ARGH = TPI/FLOAT(N) |
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| 46 | IS = 0 |
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| 47 | NFM1 = NF-1 |
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| 48 | L1 = 1 |
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| 49 | IF (NFM1 .EQ. 0) RETURN |
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| 50 | DO 110 K1=1,NFM1 |
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| 51 | IP = FAC(K1+2) |
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| 52 | LD = 0 |
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| 53 | L2 = L1*IP |
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| 54 | IDO = N/L2 |
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| 55 | IPM = IP-1 |
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| 56 | DO 109 J=1,IPM |
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| 57 | LD = LD+L1 |
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| 58 | I = IS |
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| 59 | ARGLD = FLOAT(LD)*ARGH |
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| 60 | FI = 0. |
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| 61 | DO 108 II=3,IDO,2 |
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| 62 | I = I+2 |
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| 63 | FI = FI+1. |
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| 64 | ARG = FI*ARGLD |
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| 65 | WA(I-1) = DCOS(ARG) |
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| 66 | WA(I) = DSIN(ARG) |
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| 67 | 108 CONTINUE |
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| 68 | IS = IS+IDO |
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| 69 | 109 CONTINUE |
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| 70 | L1 = L2 |
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| 71 | 110 END DO |
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| 72 | RETURN |
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| 73 | END |
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