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/*
* iemmatrix
*
* objects for manipulating simple matrices
* mostly refering to matlab/octave matrix functions
*
* (c) IOhannes m zmölnig, forum::für::umläute
*
* IEM, Graz
*
* this code is published under the LGPL
*
*/
#include "iemmatrix.h"
/* mtx_inverse */
static t_class *mtx_inverse_class;
static void mtx_inverse_matrix(t_matrix *x, t_symbol *s, int argc, t_atom *argv)
{
/* maybe we should do this in double or long double ? */
int row=atom_getfloat(argv);
int col=atom_getfloat(argv+1);
int i, k, row2=row*row;
t_matrixfloat *original, *inverted;
t_matrixfloat *a1, *a2, *b1, *b2; // dummy pointers
int ok = 0;
if(row*col+2>argc){
post("mtx_print : sparse matrices not yet supported : use \"mtx_check\"");
return;
}
if (row!=col){
post("mtx_inverse: only square matrices can be inverted");
return;
}
// reserve memory for outputting afterwards
adjustsize(x, row, row);
// 1. get the 2 matrices : orig; invert (create as eye, but will be orig^(-1))
inverted = (t_matrixfloat *)getbytes(sizeof(t_matrixfloat)*row2);
// 1a extract values of A to float-buf
original=matrix2float(argv);
// 1b make an eye-shaped float-buf for B
i=row2;
b1=inverted;
while(i--)*b1++=0;
i=row;
b1=inverted;
while(i--)b1[i*(row+1)]=1;
// 2. do the Gauss-Jordan
for (k=0;k<row;k++) {
// 2. adjust current row
t_matrixfloat diagel = original[k*(col+1)];
t_matrixfloat i_diagel = diagel?1./diagel:0;
if (!diagel)ok++;
/* normalize current row (set the diagonal-element to 1 */
a2=original+k*col;
b2=inverted+k*col;
i=row;
while(i--){
*a2++*=i_diagel;
*b2++*=i_diagel;
}
/* eliminate the k-th element in each row by adding the weighted normalized row */
a2=original+k*row;
b2=inverted+k*row;
for(i=0;i<row;i++)
if (i-k) {
t_matrixfloat f=-*(original+i*row+k);
int j = row;
a1=original+i*row;
b1=inverted+i*row;
while (j--) {
*(a1+j)+=f**(a2+j);
*(b1+j)+=f**(b2+j);
}
}
}
// 3. output the matrix
// 3a convert the floatbuf to an atombuf;
float2matrix(x->atombuffer, inverted);
// 3b destroy the buffers
freebytes(original, sizeof(t_matrixfloat)*row2);
if (ok)post("mtx_inverse: couldn't really invert the matrix !!! %d error%c", ok, (ok-1)?'s':0);
// 3c output the atombuf;
matrix_bang(x);
}
static void *mtx_inverse_new(t_symbol *s, int argc, t_atom *argv)
{
t_matrix *x = (t_matrix *)pd_new(mtx_inverse_class);
outlet_new(&x->x_obj, 0);
x->col=x->row=0;
x->atombuffer=0;
return (x);
}
void mtx_inverse_setup(void)
{
mtx_inverse_class = class_new(gensym("mtx_inverse"), (t_newmethod)mtx_inverse_new,
(t_method)matrix_free, sizeof(t_matrix), 0, A_GIMME, 0);
class_addbang (mtx_inverse_class, matrix_bang);
class_addmethod(mtx_inverse_class, (t_method)mtx_inverse_matrix, gensym("matrix"), A_GIMME, 0);
class_sethelpsymbol(mtx_inverse_class, gensym("iemmatrix/mtx_inverse"));
}
void iemtx_inverse_setup(void){
mtx_inverse_setup();
}
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