Linear Algebra and the C Language/a09w

/* ------------------------------------ */
/*  Save as:   c00a.c                   */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
/* ------------------------------------ */
double **X_invgj_mR(
double **A,
double **invA
)
{
double **ID = i_RC_mR(A[R_SIZE][C0],A[C_SIZE][C0]);
double **AID;

int r = A[R_SIZE][C0];

  r--;

  AID = i_Abr_Ac_bc_mR(r,r,r);

          eye_mR(ID);        /* ID: Identity matrix        */
     c_A_b_Ab_mR(A,ID,AID);  /* Copy A and ID into AID     */
  invgj_pivot_mR(AID);       /* Work on the pivot          */
       sort_c_mR(AID);       /* Sort the columns           */
       sort_r_mR(AID);       /* Sort the rows              */
      c_Inv_A_mR(AID,invA);  /* Copy the inverse into invA */

  f_mR(AID);
  f_mR(ID);

return(invA);
}
/* ------------------------------------ */
/* ------------------------------------ */
void fun(int r)
{
double **A    = rE_mR( i_mR(r,r), 999.,1E-3);
double **InvA =        i_mR(r,r);

  clrscrn();

  printf(" Copy/Paste into the octave window.\n\n");
  printf("format short e\n");
  p_Octave_mR(A,"A",P4);
  printf(" inv(A)\n\n");
  
  printf(" See above for the function code: invgj_mR();\n\n InvA:");
  X_invgj_mR(A,InvA);
  pE_mR(InvA, S12,P4,C6);
 
  f_mR(InvA);
  f_mR(A);
}
/* ------------------------------------ */
int main(void)
{
time_t t;

  srand(time(&t));
  
do
{
   fun(C4);

} while(stop_w());

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

                                                                                       
 Copy/Paste into the octave window.

format short e
 A=[
+0.8370,-0.0700,+0.5320,-0.7220;
+0.6970,+0.4480,+0.8980,-0.3510;
-0.2480,-0.1110,+0.6340,-0.2010;
-0.1730,+0.2510,+0.3120,+0.6670]

 inv(A)

 See above for the function code: invgj_mR();

 InvA:
 +1.6524e+00  -6.3813e-01  -1.0430e+00  +1.1386e+00 
 -2.7307e+00  +2.6376e+00  -5.8612e-01  -1.7444e+00 
 +5.4859e-01  -1.3496e-01  +9.1512e-01  +7.9858e-01 
 +1.1996e+00  -1.0949e+00  -4.7803e-01  +2.0775e+00 


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