Linear Algebra and the C Language/a0i2

Install and compile this file in your working directory.

/* ------------------------------------ */
/*  Save as :   c00c.c                  */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
void fun(int r)
{
double **A    = rskewsymmetric_mR(   i_mR(r,r), 9);
double **invA =            inv_mR(A, i_mR(r,r));

  clrscrn();
  printf(" If Rn is even det_R(A)>0\n\n"
         " det_R(A)  = %+.4f\n\n\n",det_R(A));
         
  printf(" A:");  
  p_mR(A, S7,P3,C6);
     
  printf(" invA:");
  p_mR(invA, S7,P3,C6); 

  f_mR(A);
  f_mR(invA);
}
/* ------------------------------------ */
int main(void)
{
time_t t;

  srand(time(&t));

do
{
  fun(rp_I(R2)*R2);

} while(stop_w());

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

If the number of rows is even, the determinant is positive and we can calculate the inverse

Screen output example:

                                                                                       
 If Rn is even det_R(A)>0

 det_R(A)  = +1.0000


 A:
 +0.000  -9.000  +1.000  -8.000 
 +9.000  +0.000  -4.000  +4.000 
 -1.000  +4.000  +0.000  +3.000 
 +8.000  -4.000  -3.000  +0.000 

 invA:
 +0.000  -3.000  +4.000  +4.000 
 +3.000  +0.000  +8.000  +1.000 
 -4.000  -8.000  +0.000  +9.000 
 -4.000  -1.000  -9.000  +0.000 


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