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72 lines
1.8 KiB
Fortran
72 lines
1.8 KiB
Fortran
SUBROUTINE sla_MXM (A, B, C)
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*+
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* - - - -
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* M X M
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* - - - -
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*
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* Product of two 3x3 matrices:
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* matrix C = matrix A x matrix B
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*
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* (single precision)
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*
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* Given:
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* A real(3,3) matrix
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* B real(3,3) matrix
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*
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* Returned:
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* C real(3,3) matrix result
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*
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* To comply with the ANSI Fortran 77 standard, A, B and C must
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* be different arrays. However, the routine is coded so as to
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* work properly on many platforms even if this rule is violated.
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*
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* Last revision: 26 December 2004
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*
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* Copyright P.T.Wallace. All rights reserved.
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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REAL A(3,3),B(3,3),C(3,3)
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INTEGER I,J,K
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REAL W,WM(3,3)
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* Multiply into scratch matrix
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DO I=1,3
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DO J=1,3
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W=0.0
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DO K=1,3
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W=W+A(I,K)*B(K,J)
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END DO
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WM(I,J)=W
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END DO
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END DO
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* Return the result
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DO J=1,3
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DO I=1,3
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C(I,J)=WM(I,J)
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END DO
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END DO
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END
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