Linear Algebra and the C Language/a0jo

/* ------------------------------------ */
/*  Save as :   c00c.c                  */
/* ------------------------------------ */
#include "v_a.h"
/* ------------------------------------ */
#define   RA R5
#define   CA C5    
/* ------------------------------------ */
int main(void)
{
double xy[6] ={
   1,     10,
   2,      1,
   3,    -10    };
   
double tA[RA*CA]={
/* x**2     y**2     x        y        e     */
  +1,      +0,      +0,      +0,      +0, 
  +0,      +1,      +0,      +0,      +0,   
  +1,    +100,      +1,     +10,      +1, 
  +4,      +1,      +2,      +1,      +1,    
  +9,    +100,      +3,     -10,      +1,      
};

double tb[RA*C1]={
/*   = 0   */
      +1,   
      +1,   
      +0,   
      +0,   
      +0,  
};

double **XY      = ca_A_mR(xy,i_mR(R3,C2));
double **A       = ca_A_mR(tA,i_mR(RA,CA));
double **b       = ca_A_mR(tb,i_mR(RA,C1));
double **Inv    = i_mR(CA,RA);           
double **Invb   = i_mR(CA,C1);          

  clrscrn();
  printf("\n");
  printf(" Find the coefficients a, b, c, d,  of a circle  \n\n");
  printf("     ax**2 + ay**2 + bx + cy + d  = 0            \n\n");
  printf(" that passes through these three XY.         \n\n");
  printf("    x     y");
  p_mR(XY,S5,P0,C6);
  stop();
  
  clrscrn(); 
  printf(" Using the given XY, we obtain this matrix.\n");
  printf("  (a = 1. This is my choice)\n\n");
  printf(" A :");
  p_mR(A,S10,P2,C7);
  printf(" b :");
  p_mR(b,S10,P2,C7);
   
  printf(" Inv :");
  invgj_mR(A,Inv); 
  pE_mR(Inv,S12,P4,C10); 
  stop();
  
  clrscrn(); 
  printf(" Inv :"); 
  p_mR(Inv,S10,P4,C10);  
  
  printf(" x = Inv * b ");   
  mul_mR(Inv,b,Invb); 
  p_mR(Invb,S10,P4,C10);
  printf(" The coefficients a, b, c, d, e, of the curve are : \n\n"
         "  %+.2fx**2 %+.2fy**2 %+.2fx %+.2fy %+.2f = 0\n\n"
            ,Invb[R1][C1],Invb[R2][C1],Invb[R3][C1],
             Invb[R4][C1],Invb[R5][C1]);       
  stop(); 
   
  f_mR(XY);    
  f_mR(A);
  f_mR(b); 
  f_mR(Inv);
  f_mR(Invb); 
  
  return 0;
}
/* ------------------------------------ */
/* ------------------------------------ */

 Find the coefficients a, b, c, d,  of a circle  

     ax**2 + ay**2 + bx + cy + d  = 0            

 that passes through these three XY.         

    x     y
   +1   +10 
   +2    +1 
   +3   -10 

 Press return to continue. 


 Using the given XY, we obtain this matrix.
  (a = 1. This is my choice)

 A :
     +1.00      +0.00      +0.00      +0.00      +0.00 
     +0.00      +1.00      +0.00      +0.00      +0.00 
     +1.00    +100.00      +1.00     +10.00      +1.00 
     +4.00      +1.00      +2.00      +1.00      +1.00 
     +9.00    +100.00      +3.00     -10.00      +1.00 

 b :
     +1.00 
     +1.00 
     +0.00 
     +0.00 
     +0.00 

 Inv :
 +1.0000e+00  +0.0000e+00  -4.4409e-16  +8.8818e-16  +4.4409e-16 
 +2.7756e-17  +1.0000e+00  -2.0817e-17  -1.3878e-17  -3.4694e-17 
 +6.0000e+00  +9.9000e+02  -5.5000e+00  +1.0000e+01  -4.5000e+00 
 +1.0000e+00  +9.9000e+01  -5.0000e-01  +1.0000e+00  -5.0000e-01 
 -1.7000e+01  -2.0800e+03  +1.1500e+01  -2.0000e+01  +9.5000e+00 

 Press return to continue. 


 Inv :
   +1.0000    +0.0000    -0.0000    +0.0000    +0.0000 
   +0.0000    +1.0000    -0.0000    -0.0000    -0.0000 
   +6.0000  +990.0000    -5.5000   +10.0000    -4.5000 
   +1.0000   +99.0000    -0.5000    +1.0000    -0.5000 
  -17.0000 -2080.0000   +11.5000   -20.0000    +9.5000 

 x = Inv * b 
   +1.0000 
   +1.0000 
 +996.0000 
 +100.0000 
-2097.0000 

 The coefficients a, b, c, d, e, of the curve are : 

  +1.00x**2 +1.00y**2 +996.00x +100.00y -2097.00 = 0

 Press return to continue.