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/* Multiply two matrices.
*
* Copyright: 1990, K. Martinez and J. Cupitt
*
* 23/10/10
* - gtk-doc
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 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>
/**
* im_matmul:
* @in1: input matrix
* @in2: input matrix
* @filename: name for output matrix
*
* Multiplies two DOUBLEMASKs. Result matrix is made and returned.
* Pass the filename to set for the output.
*
* The scale and offset members of @in1 and @in2 are ignored.
*
* See also: im_mattrn(), im_matinv().
*
* Returns: the result matrix on success, or %NULL on error.
*/
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_error( "im_matmul", "%s", _( "bad sizes" ) );
return( NULL );
}
/* Allocate output matrix.
*/
if( !(mat = im_create_dmask( name, in2->xsize, in1->ysize )) )
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 );
}
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