libvips/libsrc/matrix/im_matmul.c

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2007-08-29 18:23:50 +02:00
/* @(#) Multiplies two DOUBLEMASKs. Result matrix is made and returned.
* @(#) Pass the filename to set for the output.
* @(#)
* @(#) DOUBLEMASK *
* @(#) im_matmul( in1, in2, name )
* @(#) DOUBLEMASK *in1, *in2;
* @(#) char *name;
* @(#)
* @(#) NULL for error.
*
* Copyright: 1990, K. Martinez and J. Cupitt
*
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* MATRIX MULTIPLY?
*/
DOUBLEMASK *
im_matmul( DOUBLEMASK *in1, DOUBLEMASK *in2, const char *name )
{
int xc, yc, col;
double sum;
DOUBLEMASK *mat;
double *out, *a, *b;
double *s1, *s2;
/* Check matrix sizes.
*/
if( in1->xsize != in2->ysize ) {
im_errormsg( "im_matmul: bad sizes" );
return( NULL );
}
/* Allocate output matrix.
*/
if( !(mat = im_create_dmask( name, in2->xsize, in1->ysize )) ) {
im_errormsg( "im_matmul: unable to allocate output mask" );
return( NULL );
}
/* Multiply.
*/
out = mat->coeff;
s1 = in1->coeff;
for( yc = 0; yc < in1->ysize; yc++ ) {
s2 = in2->coeff;
for( col = 0; col < in2->xsize; col++ ) {
/* Get ready to sweep a row.
*/
sum = 0.0;
a = s1;
b = s2;
for( sum = 0.0, xc = 0; xc < in1->xsize; xc++ ) {
sum += *a++ * *b;
b += in2->xsize;
}
*out++ = sum;
s2++;
}
s1 += in1->xsize;
}
return( mat );
}