Linear Algebra and the C Language/a0bs

Install and compile this file in your working directory.

/* ------------------------------------ */
/*  Save as :   c00c.c                  */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
void fun(int r)
{
double **A   =       r_Q_mR(        i_mR(r,r), 9);
double **B   =       r_Q_mR(        i_mR(r,r), 9);
double **AB  =       mul_mR(A,B,    i_mR(r,r));
double **ABT = transpose_mR(AB,     i_mR(r,r));
double **T   =       mul_mR(AB,ABT, i_mR(r,r));

  clrscrn();
  printf(" A:                 an orthonormal matrix ");
  p_mR(A,S3,P3,C6); 
  printf(" B:                 an orthonormal matrix ");
  p_mR(B,S3,P3,C6);
  stop();

  clrscrn();
  printf("   A B  = AB        AB is an orthonormal matrix");
  p_mR(AB,S3,P3,C6);    
  printf(" AB ABT = id        inv(AB) = ABT ");
  p_mR(T,S3,P3,C6);    
  
  f_mR(A);
  f_mR(B);
  f_mR(AB);
  f_mR(ABT);
  f_mR(T);
}
/* ------------------------------------ */
int main(void)
{
time_t t;

  srand(time(&t));

do
{
  fun(rp_I(R3) + R2);

} while(stop_w());

  return 0;
}
/* ------------------------------------ */
/* ------------------------------------ */

Screen output example:

                                                                                       
 A:                 an orthonormal matrix 
-0.331 -0.915 +0.230 
+0.579 -0.004 +0.815 
-0.745 +0.403 +0.532 

 B:                 an orthonormal matrix 
+0.811 -0.479 -0.336 
+0.487 +0.871 -0.067 
+0.324 -0.109 +0.940 

 Press return to continue. 


   A B  = AB        AB is an orthonormal matrix
-0.639 -0.664 +0.389 
+0.732 -0.370 +0.572 
-0.235 +0.650 +0.722 

 AB ABT = id        inv(AB) = ABT 
+1.000 -0.000 +0.000 
-0.000 +1.000 +0.000 
+0.000 +0.000 +1.000 


 Press   return to continue
 Press X return to stop