Linear Algebra and the C Language/a0m0


Install and compile this file in your working directory.

/* ------------------------------------ */
/*  Save as :   c02a.c                  */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
#define   RCA R4
/* ------------------------------------ */
int main(void)
{
double a[RCA*RCA]={
+5.701637292731, +0.991969965586, +0.254041088748, +1.125039107310, 
+0.991969965586, +6.402440296173, +0.359161539264, +1.590572531025, 
+0.254041088748, +0.359161539264, +5.091980394202, +0.407341745750, 
+1.125039107310, +1.590572531025, +0.407341745750, +6.803942016894    
};

double **A      = ca_A_mR(a, i_mR(RCA,RCA));
double **EValue = eigs_mR(A, i_mR(RCA,R1));

  clrscrn();
  printf(" The eigenvectors associated with eigenvalues\n"
         " with multiple multiplicity are not unique.  \n"
         " There exist several set of unit vectors that\n"
         " correspond to the same eigenspace.      \n\n\n"
         
         " Copy/Paste into the octave windows\n\n");
  p_Octave_mR(A,"a",P9);
  printf(" [V, E] = eigs (a,%d) \n\n",RCA);
  
  printf(" EValue:");
  p_mR(EValue,S10,P3,C10); 
          
  stop();

  f_mR(A);
  f_mR(EValue); 

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

Screen output example:

                                                                                       
 The eigenvectors associated with eigenvalues
 with multiple multiplicity are not unique.  
 There exist several set of unit vectors that
 correspond to the same eigenspace.      


 Copy/Paste into the octave windows

 a=[
+5.701637293,+0.991969966,+0.254041089,+1.125039107;
+0.991969966,+6.402440296,+0.359161539,+1.590572531;
+0.254041089,+0.359161539,+5.091980394,+0.407341746;
+1.125039107,+1.590572531,+0.407341746,+6.803942017]

 [V, E] = eigs (a,4) 

 EValue:
    +9.000 
    +5.000 
    +5.000 
    +5.000 

 Press return to continue.