| 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: cosq1b.f,v 1.2 2004/06/15 21:08:32 rodney Exp $ |
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| 11 | ! |
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| 12 | !CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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| 13 | |
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| 14 | SUBROUTINE COSQ1B (N, INC, X, LENX, WSAVE, LENSAV, & |
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| 15 | & WORK, LENWRK, IER) |
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| 16 | INTEGER N, INC, LENX, LENSAV, LENWRK, IER |
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| 17 | REAL X(INC,*), WSAVE(LENSAV), WORK(LENWRK) |
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| 18 | ! |
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| 19 | IER = 0 |
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| 20 | ! |
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| 21 | IF (LENX .LT. INC*(N-1) + 1) THEN |
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| 22 | IER = 1 |
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| 23 | CALL XERFFT ('COSQ1B', 6) |
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| 24 | GO TO 300 |
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| 25 | ELSEIF (LENSAV .LT. 2*N + INT(LOG(REAL(N))) +4) THEN |
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| 26 | IER = 2 |
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| 27 | CALL XERFFT ('COSQ1B', 8) |
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| 28 | GO TO 300 |
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| 29 | ELSEIF (LENWRK .LT. N) THEN |
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| 30 | IER = 3 |
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| 31 | CALL XERFFT ('COSQ1B', 10) |
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| 32 | GO TO 300 |
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| 33 | ENDIF |
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| 34 | ! |
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| 35 | IF (N-2) 300,102,103 |
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| 36 | 102 SSQRT2 = 1./SQRT(2.) |
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| 37 | X1 = X(1,1)+X(1,2) |
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| 38 | X(1,2) = SSQRT2*(X(1,1)-X(1,2)) |
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| 39 | X(1,1) = X1 |
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| 40 | RETURN |
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| 41 | 103 CALL COSQB1 (N,INC,X,WSAVE,WORK,IER1) |
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| 42 | IF (IER1 .NE. 0) THEN |
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| 43 | IER = 20 |
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| 44 | CALL XERFFT ('COSQ1B',-5) |
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| 45 | ENDIF |
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| 46 | ! |
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| 47 | 300 RETURN |
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| 48 | END |
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