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Diffstat (limited to 'math/slalib/mxm.f')
| -rw-r--r-- | math/slalib/mxm.f | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/math/slalib/mxm.f b/math/slalib/mxm.f new file mode 100644 index 00000000..1c00c632 --- /dev/null +++ b/math/slalib/mxm.f @@ -0,0 +1,72 @@ + SUBROUTINE slMXM (A, B, C) +*+ +* - - - - +* M X M +* - - - - +* +* Product of two 3x3 matrices: +* matrix C = matrix A x matrix B +* +* (single precision) +* +* Given: +* A real(3,3) matrix +* B real(3,3) matrix +* +* Returned: +* C real(3,3) matrix result +* +* To comply with the ANSI Fortran 77 standard, A, B and C must +* be different arrays. However, the routine is coded so as to +* work properly on many platforms even if this rule is violated. +* +* Last revision: 26 December 2004 +* +* Copyright P.T.Wallace. All rights reserved. +* +* License: +* This program is free software; you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published by +* the Free Software Foundation; either version 2 of the License, or +* (at your option) any later version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with this program (see SLA_CONDITIONS); if not, write to the +* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, +* Boston, MA 02110-1301 USA +* +* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. +*- + + IMPLICIT NONE + + REAL A(3,3),B(3,3),C(3,3) + + INTEGER I,J,K + REAL W,WM(3,3) + + +* Multiply into scratch matrix + DO I=1,3 + DO J=1,3 + W=0.0 + DO K=1,3 + W=W+A(I,K)*B(K,J) + END DO + WM(I,J)=W + END DO + END DO + +* Return the result + DO J=1,3 + DO I=1,3 + C(I,J)=WM(I,J) + END DO + END DO + + END |