1IM_MATINV(3)               Library Functions Manual               IM_MATINV(3)
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NAME

6       im_matinv, im_matmul, im_mattrn - matrix operations on DOUBLEMASKs
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SYNOPSIS

10       #include <vips/vips.h>
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12       DOUBLEMASK *im_matinv( in, name )
13       DOUBLEMASK *in;
14       char *name;
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16       DOUBLEMASK *im_matmul( in1, in2, name )
17       DOUBLEMASK *in1, *in2;
18       char *name;
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20       DOUBLEMASK *im_matcat( in1, in2, name )
21       DOUBLEMASK *in1, *in2;
22       char *name;
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24       DOUBLEMASK *im_mattrn( in, name )
25       DOUBLEMASK *in;
26       char *name;
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DESCRIPTION

30       These  functions treat DOUBLEMASKs as matricies, performing some of the
31       basics of matrix algebra on them. Code for  im_matinv  was  taken  from
32       Numerical Recipies in C, thanks!
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34       There should be more matrix functions: those implemeneted are just suf‐
35       ficient for the Gallery's calibration routines. im_matadd,  im_matiden‐
36       tity should really be added.
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38       None of these functions damage their arguments.
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40       im_matinv()  inverts DOUBLEMASK in , returning a new DOUBLEMASK, called
41       name , which contains the inverse of in. If no inverse exists. NULL  is
42       returned and im_errorstring set to a diagnostic message.
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44       im_matmul() multiples the matrices held in in1 and in2, returning their
45       product in a matrix called name.
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47       im_matcat() returns a new matrix formed by appending matrix in2 to  the
48       end  of  matrix  in1.   The two matricies must be the same width. It is
49       useful for combining several im_measure()s into a single matrix.
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51       im_mattrn() transposes matrix in, returning the transpose in new matrix
52       called name.
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RETURN VALUE

55       The functions returns a new DOUBLEMASK on sucess, and NULL on failure.
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SEE ALSO

58       im_create_dmask(3), im_measure(3), etc.
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61       National Gallery, 1992
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AUTHOR

64       J. Cupitt
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68                                  2 May 1991                      IM_MATINV(3)
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