aboutsummaryrefslogtreecommitdiff
path: root/src/mtx_inverse.c
diff options
context:
space:
mode:
authorIOhannes m zmölnig <zmoelnig@users.sourceforge.net>2005-03-21 14:33:31 +0000
committerIOhannes m zmölnig <zmoelnig@users.sourceforge.net>2005-03-21 14:33:31 +0000
commit10b474fba485e9a93157c7fa534bb66e7bcc6fde (patch)
tree73e9e02738ea62179a1722b37ef49a9e91cfcbad /src/mtx_inverse.c
This commit was generated by cvs2svn to compensate for changes in r2637,svn2git-root
which included commits to RCS files with non-trunk default branches. svn path=/trunk/externals/iem/iemmatrix/; revision=2638
Diffstat (limited to 'src/mtx_inverse.c')
-rw-r--r--src/mtx_inverse.c118
1 files changed, 118 insertions, 0 deletions
diff --git a/src/mtx_inverse.c b/src/mtx_inverse.c
new file mode 100644
index 0000000..400f734
--- /dev/null
+++ b/src/mtx_inverse.c
@@ -0,0 +1,118 @@
+/*
+ * iemmatrix
+ *
+ * objects for manipulating simple matrices
+ * mostly refering to matlab/octave matrix functions
+ *
+ * (c) IOhannes m zmlnig, forum::fr::umlute
+ *
+ * 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();
+}