Linear Algebra and the C Language/a0ct


Install and compile this file in your working directory.

/* ------------------------------------ */
/*  Save as :   c00b.c                  */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */     
#define RCA          RC3  
/* ------------------------------------ */       
/* ------------------------------------ */
int main(void)
{                          
double a[RCA*RCA] ={   
+0.390117647059, +0.169411764706, +0.457411764706, 
+0.169411764706, +0.952941176471, -0.127058823529, 
+0.457411764706, -0.127058823529, +0.656941176471                 
};
                       
double **A      =   ca_A_mR(a, i_mR(RCA,RCA));
double **V      = eigs_V_mR(A, i_mR(RCA,RCA));
double **invV   =  invgj_mR(V, i_mR(RCA,RCA));
double **EValue =              i_mR(RCA,RCA);

double **T      =              i_mR(RCA,RCA);

  clrscrn(); 
  printf(" A :");
  p_mR(A, S8,P6, C3);     

  printf(" V :");
  p_mR(V, S9,P6, C4); 
 
  printf(" EValue = invV * A * V");
  mul_mR(invV,A,T);
  mul_mR(T,V,EValue);
  p_mR(EValue, S9,P6, C4); 
          
  printf("\n\n"
         " A = V * EValue * invV        (Just verify the computation)");
  mul_mR(V,EValue,T);
  mul_mR(T,invV,A); 
  p_mR(A, S8,P6, C3);
  stop();
  
  clrscrn();
  printf(" V1        V2        V3 :");
  p_mR(V, S9,P6, C4); 
   
  printf(" EValue1   EValue2   EValue3 ");
  p_mR(EValue, S9,P6, C4); 
  
  printf(" det(V)  = %.3e\n"
         " det(V) != 0.00 V1 and V2 and V3 are linearly independent\n\n",
         det_R(V));  
                    
  printf(" The matrix A projects the space in the direction\n"
         " of the  eigenvector V3  on a plan  determined by\n"
         " the eigenvector V1 and V2 if :\n\n"
         " The eigenvector V1 has its eigenvalue equal to  one and   \n"
         " The eigenvector V2 has its eigenvalue equal to  one and   \n"
         " The eigenvector V3 has its eigenvalue equal to zero and \n\n"
         " If The vectors V1 and V2 and V3 are linearly independent\n\n");                
  stop();  
  
  f_mR(A);
  f_mR(V);  
  f_mR(invV);  
  f_mR(T);  
  f_mR(EValue);

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


Screen output example:

                                                                                       
 A :
+0.390118 +0.169412 +0.457412 
+0.169412 +0.952941 -0.127059 
+0.457412 -0.127059 +0.656941 

 V :
+0.173564 +0.173839 +0.780950 
+0.976187 +0.976187 -0.216930 
-0.130131 -0.129765 -0.585712 

 EValue = invV * A * V
+1.000000 -0.000000 +0.000000 
+0.000000 +1.000000 -0.000000 
+0.000000 +0.000000 +0.000000 



 A = V * EValue * invV        (Just verify the computation)
+0.390118 +0.169412 +0.457412 
+0.169412 +0.952941 -0.127059 
+0.457412 -0.127059 +0.656941 

 Press return to continue. 


 V1        V2        V3 :
+0.173564 +0.173839 +0.780950 
+0.976187 +0.976187 -0.216930 
-0.130131 -0.129765 -0.585712 

 EValue1   EValue2   EValue3 
+1.000000 -0.000000 +0.000000 
+0.000000 +1.000000 -0.000000 
+0.000000 +0.000000 +0.000000 

 det(V)  = 4.582e-04
 det(V) != 0.00 V1 and V2 and V3 are linearly independent

 The matrix A projects the space in the direction
 of the  eigenvector V3  on a plan  determined by
 the eigenvector V1 and V2 if :

 The eigenvector V1 has its eigenvalue equal to  one and   
 The eigenvector V2 has its eigenvalue equal to  one and   
 The eigenvector V3 has its eigenvalue equal to zero and 

 If The vectors V1 and V2 and V3 are linearly independent

 Press return to continue.