Mathc matrices/c09a03

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	inv03.c

/* ------------------------------------ */
/*  Save as :   inv03.c                 */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
/* ------------------------------------ */
/* ------------------------------------ */
double **XX_invgj_pivot_mR(
double **Ab
)
{
double pivot = 1.;

int r= R1;

    while( pivot &&
          (r<Ab[R_SIZE  ][C0])
         )
       {
        pivot = pivotbestAId_mR(Ab,r);
        
        if(pivot>ERROR_E) 
                 zero_under_pivot_gj1Ab_mR(Ab,r);
        r++;
       }

    while( (r>R1) )
       {
		 r--;
         zero_below_pivot_gj1Ab_mR(Ab,r);
	    }
        
return(Ab);
}
/* ------------------------------------ */
/* ------------------------------------ */
double **XX_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);
   XX_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   = r_mR( i_mR(r,r), 99.);
double **Inv =       i_mR(r,r);
double **AInv =      i_mR(r,r);

  clrscrn();
  
  XX_invgj_mR(A,Inv);
  
  printf(" Copy/Past into the octave window.\n\n");
  printf("format short e\n");
  p_Octave_mR(A,"A",P0);
  
  printf(" inv(A)");
  pE_mR(Inv,S12,P4,C6);

  printf(" A * inv(A)");
  mul_mR(A,Inv,AInv);
  p_mR(AInv,S12,P4,C6);
  
  f_mR(AInv);  
  f_mR(Inv);
  f_mR(A);
}
/* ------------------------------------ */
int main(void)
{
time_t t;

  srand(time(&t));
  
do
{
   fun(rp_I(C2)+C2);

} while(stop_w());

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

Nous allons étudier la fonction invgj_pivot_mR();. Comme cette fonction existe dans la bibliothèque, nous allons l'appeler XX_invgj_pivot_mR();


Exemple de sortie écran :

 ------------------------------------ 
 Copy/Past into the octave window.

format short e
 A=[
-81,-13,+40;
+70,+64,+78;
+64,+76,+54]

 inv(A)
 -1.0590e-02  +1.6030e-02  -1.5310e-02 
 +5.1920e-03  -2.9704e-02  +3.9060e-02 
 +5.2434e-03  +2.2807e-02  -1.8309e-02 

 A * inv(A)
     +1.0000      -0.0000      -0.0000 
     -0.0000      +1.0000      +0.0000 
     +0.0000      -0.0000      +1.0000 


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