Linear Algebra and the C Language/a0kt

/* ------------------------------------ */
/*  Save as:   c00c.c                   */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
/* ------------------------------------ */
double **X_invgj_pivot_mR(
double **Ab
)
{
double pivot = 1.;

int r= R1;

    while( pivot &&
          (r<Ab[R_SIZE  ][C0]) 
         )
       {                         
        pivot = pivotbestAId_mR(Ab,r);       /* Select the best pivot */
        
        if(pivot>ERROR_E) 
            zero_under_pivot_gj1Ab_mR(Ab,r); /* zero under the pivot  */
        r++;
       }

    while( (r>R1) )
       {
		 r--;
         zero_above_pivot_gj1Ab_mR(Ab,r);     /* zero above the pivot */
	    }
        
return(Ab);
}
/* ------------------------------------ */
/* ------------------------------------ */
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);
  c_A_b_Ab_mR(A,ID,AID);
   X_invgj_pivot_mR(AID);
    sort_c_mR(AID);
    sort_r_mR(AID);
   c_Inv_A_mR(AID,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();
  
  X_invgj_mR(A,InvA);
  
  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_pivot_mR();\n\n"
         " 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=[
+0.4020,+0.0880,+0.8280,-0.1620;
-0.0950,+0.6660,-0.3740,+0.8680;
-0.4290,+0.4750,+0.7460,+0.2280;
+0.9240,+0.3070,+0.5860,-0.9630]

 inv(A)

 See above for the function code: invgj_pivot_mR();

 InvA:
 +1.2509e+00  +6.1299e-01  -1.1382e+00  +7.2610e-02 
 -1.1435e+00  +6.1994e-01  +8.3469e-01  +9.4876e-01 
 +1.0051e+00  -2.3810e-01  +3.4312e-01  -3.0246e-01 
 +1.4474e+00  +6.4091e-01  -6.1717e-01  -8.5034e-01 


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