| [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: xercon.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 | LOGICAL FUNCTION XERCON (INC,JUMP,N,LOT) |
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| 15 | INTEGER INC, JUMP, N, LOT |
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| 16 | INTEGER I, J, JNEW, LCM |
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| 17 | ! |
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| 18 | ! Definition: positive integers INC, JUMP, N and LOT are consistent |
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| 19 | ! ---------- |
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| 20 | ! if I1*INC + J1*JUMP = I2*INC + J2*JUMP for I1,I2 < N and J1,J2 |
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| 21 | ! < LOT implies I1=I2 and J1=J2. |
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| 22 | ! |
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| 23 | ! For multiple FFTs to execute correctly, input parameters INC, |
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| 24 | ! JUMP, N and LOT must be consistent ... otherwise at least one |
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| 25 | ! array element mistakenly is transformed more than once. |
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| 26 | ! |
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| 27 | ! XERCON = .TRUE. if and only if INC, JUMP, N and LOT are |
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| 28 | ! consistent. |
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| 29 | ! |
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| 30 | ! ------------------------------------------------------------------ |
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| 31 | ! |
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| 32 | ! Compute I = greatest common divisor (INC, JUMP) |
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| 33 | ! |
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| 34 | I = INC |
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| 35 | J = JUMP |
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| 36 | 10 CONTINUE |
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| 37 | IF (J .NE. 0) THEN |
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| 38 | JNEW = MOD(I,J) |
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| 39 | I = J |
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| 40 | J = JNEW |
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| 41 | GO TO 10 |
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| 42 | ENDIF |
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| 43 | ! |
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| 44 | ! Compute LCM = least common multiple (INC, JUMP) |
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| 45 | ! |
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| 46 | LCM = (INC*JUMP)/I |
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| 47 | ! |
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| 48 | ! Check consistency of INC, JUMP, N, LOT |
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| 49 | ! |
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| 50 | IF (LCM .LE. (N-1)*INC .AND. LCM .LE. (LOT-1)*JUMP) THEN |
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| 51 | XERCON = .FALSE. |
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| 52 | ELSE |
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| 53 | XERCON = .TRUE. |
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| 54 | ENDIF |
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| 55 | ! |
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| 56 | RETURN |
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| 57 | END |
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