IM_MATINV(3X)

NAME
im_matinv, im_matmul, im_mattrn - matrix operations on DOUBLEMASKs

SYNOPSIS
#include <vips/vips.h> DOUBLEMASK *im_matinv( in, name )
DOUBLEMASK *in;
char *name; DOUBLEMASK *im_matmul( in1, in2, name )
DOUBLEMASK *in1, *in2;
char *name; DOUBLEMASK *im_matcat( in1, in2, name )
DOUBLEMASK *in1, *in2;
char *name; DOUBLEMASK *im_mattrn( in, name )
DOUBLEMASK *in;
char *name;

DESCRIPTION
These functions treat DOUBLEMASKs as matricies, performing some of the basics of matrix algebra on them. Code for im_matinv was taken from Numerical Recipies in C, thanks! There should be more matrix functions: those implemeneted are just sufficient for the Gallery's calibration routines. im_matadd, im_matidentity should really be added. None of these functions damage their arguments. im_matinv() inverts DOUBLEMASK in , returning a new DOUBLEMASK, called name , which contains the inverse of in. If no inverse exists. NULL is returned and im_errorstring set to a diagnostic message. im_matmul() multiples the matrices held in in1 and in2, returning their product in a matrix called name. im_matcat() returns a new matrix formed by appending matrix in2 to the end of matrix in1. The two matricies must be the same width. It is useful for combining several im_measure()s into a single matrix. im_mattrn() transposes matrix in, returning the transpose in new matrix called name.

RETURN VALUE
The functions returns a new DOUBLEMASK on sucess, and NULL on failure.

SEE ALSO
im_create_dmask(3X), im_measure(3X), etc.

COPYRIGHT
National Gallery, 1992

AUTHOR
J. Cupitt