111 lines
2.3 KiB
C
111 lines
2.3 KiB
C
/* Multiply two matrices.
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*
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* Copyright: 1990, K. Martinez and J. Cupitt
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*
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* 23/10/10
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* - gtk-doc
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser 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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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 Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <glib/gi18n-lib.h>
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#include <stdio.h>
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#include <vips/vips.h>
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#include <vips/vips7compat.h>
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/**
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* im_matmul:
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* @in1: input matrix
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* @in2: input matrix
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* @filename: name for output matrix
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*
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* Multiplies two DOUBLEMASKs. Result matrix is made and returned.
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* Pass the filename to set for the output.
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*
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* The scale and offset members of @in1 and @in2 are ignored.
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*
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* See also: im_mattrn(), im_matinv().
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*
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* Returns: the result matrix on success, or %NULL on error.
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*/
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DOUBLEMASK *
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im_matmul( DOUBLEMASK *in1, DOUBLEMASK *in2, const char *name )
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{
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int xc, yc, col;
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double sum;
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DOUBLEMASK *mat;
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double *out, *a, *b;
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double *s1, *s2;
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/* Check matrix sizes.
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*/
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if( in1->xsize != in2->ysize ) {
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im_error( "im_matmul", "%s", _( "bad sizes" ) );
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return( NULL );
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}
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/* Allocate output matrix.
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*/
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if( !(mat = im_create_dmask( name, in2->xsize, in1->ysize )) )
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return( NULL );
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/* Multiply.
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*/
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out = mat->coeff;
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s1 = in1->coeff;
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for( yc = 0; yc < in1->ysize; yc++ ) {
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s2 = in2->coeff;
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for( col = 0; col < in2->xsize; col++ ) {
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/* Get ready to sweep a row.
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*/
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sum = 0.0;
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a = s1;
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b = s2;
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for( sum = 0.0, xc = 0; xc < in1->xsize; xc++ ) {
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sum += *a++ * *b;
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b += in2->xsize;
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}
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*out++ = sum;
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s2++;
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}
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s1 += in1->xsize;
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}
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return( mat );
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}
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