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authorIOhannes m zmölnig <zmoelnig@users.sourceforge.net>2005-05-09 16:31:56 +0000
committerIOhannes m zmölnig <zmoelnig@users.sourceforge.net>2005-05-09 16:31:56 +0000
commit8d990633f60eadf79e714fab3b1326164d38d0c3 (patch)
tree68b241c1009637d9aea555ed366018cce4fbc4a4 /src/mtx_gauss.c
parentdc15d41e8b4ec760e1ba3378683656c0d29469d8 (diff)
a simple gauss elimination (without pivoting)
svn path=/trunk/externals/iem/iemmatrix/; revision=2929
Diffstat (limited to 'src/mtx_gauss.c')
-rw-r--r--src/mtx_gauss.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/src/mtx_gauss.c b/src/mtx_gauss.c
new file mode 100644
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--- /dev/null
+++ b/src/mtx_gauss.c
@@ -0,0 +1,124 @@
+/*
+ * iemmatrix
+ *
+ * objects for manipulating simple matrices
+ * mostly refering to matlab/octave matrix functions
+ *
+ * Copyright (c) IOhannes m zmlnig, forum::fr::umlute
+ * IEM, Graz, Austria
+ *
+ * For information on usage and redistribution, and for a DISCLAIMER OF ALL
+ * WARRANTIES, see the file, "LICENSE.txt," in this distribution.
+ *
+ */
+#include "iemmatrix.h"
+
+/* mtx_gauss */
+
+/*
+ * gauss elimination of a matrix (without semi-pivoting)
+ */
+
+static t_class *mtx_gauss_class;
+
+static void mtx_gauss_xch(t_matrixfloat*a, t_matrixfloat*b, int count){
+ while(count--){
+ t_matrixfloat dummy=*a;
+ *a++=*b;
+ *b++=dummy;
+ }
+}
+static void mtx_gauss_mulsub(t_matrixfloat*a, t_matrixfloat*b, int count, t_matrixfloat f){
+ t_matrixfloat f2=1./f;
+ while(count--){
+ t_matrixfloat dummy=(f* (*b) - *a++)*f2;
+ *b++=dummy;
+ }
+}
+
+static void mtx_gauss_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, j, k, row2=row*row;
+
+ t_matrixfloat *original, *gaussed;
+ t_matrixfloat *a1, *a2, *b1, *b2; // dummy pointers
+
+ int ok = 0;
+ int I;
+
+ if(row*col+2>argc){
+ post("mtx_print : sparse matrices not yet supported : use \"mtx_check\"");
+ return;
+ }
+ if (row!=col){
+ post("mtx_gauss: only square matrices can be gauss eliminated");
+ return;
+ }
+
+ // reserve memory for outputting afterwards
+ adjustsize(x, row, row);
+ original=matrix2float(argv);
+
+ const t_matrixfloat singrange = 1.0e-10;
+ // Gauss elimination
+ for(i=0; i<row; i++) {
+ int nz = 0;
+ a1=original+i*(col+1);
+ for(j=i; j<row; j++){
+ const t_matrixfloat f=*a1;
+ if((f>singrange)||(f<-singrange)){
+ nz=j;
+ break;
+ }
+ a1+=col;
+ }
+ //if(nz)
+ {
+ // exchange rows "nz" and "i"
+ if(nz != i)mtx_gauss_xch(original+i*col+i, original+nz*col+i, col-i);
+
+ //
+ for(j=i+1; j<row; j++){
+ t_matrixfloat f=0.;
+ a1=original+i*(col+1);
+ a2=original+j*col+i;
+ if(*a2){
+ f=*a1 / *a2;
+ mtx_gauss_mulsub(a1, a2, col-i, f);
+ }
+ }
+ }
+ }
+
+ // 3. output the matrix
+ // 3a convert the floatbuf to an atombuf;
+ float2matrix(x->atombuffer, original);
+
+ // 3c output the atombuf;
+ matrix_bang(x);
+}
+
+static void *mtx_gauss_new(t_symbol *s, int argc, t_atom *argv)
+{
+ t_matrix *x = (t_matrix *)pd_new(mtx_gauss_class);
+ outlet_new(&x->x_obj, 0);
+ x->col=x->row=0;
+ x->atombuffer=0;
+
+ return (x);
+}
+void mtx_gauss_setup(void)
+{
+ mtx_gauss_class = class_new(gensym("mtx_gauss"), (t_newmethod)mtx_gauss_new,
+ (t_method)matrix_free, sizeof(t_matrix), 0, A_GIMME, 0);
+ class_addbang (mtx_gauss_class, matrix_bang);
+ class_addmethod(mtx_gauss_class, (t_method)mtx_gauss_matrix, gensym("matrix"), A_GIMME, 0);
+ class_sethelpsymbol(mtx_gauss_class, gensym("iemmatrix/mtx_gauss"));
+}
+
+void iemtx_gauss_setup(void){
+ mtx_gauss_setup();
+}