EQUATION DU 2ND DEGRÉE DANS C

/* ---------------------------------------------- */
/* secgdeg.C: Resolution d'une equation du second */
/*            degree                              */
/* ---------------------------------------------- */

/* En-tete */
#include<stdio.h>
#include<math.h>

/* Structure */
struct complexe
{
     float za; /* Partie Reel */
     float zb; /* Partie Imaginaire */
};

/* Variables globales */
struct complexe x1, x2; /* Racines du polynome */
const char carre = (char)253; /* caractere 'carre'*/
struct complexe A, B, C; /* Coefficient complexe */

/* Prototypes des fonctions: */
void ResEq2Deg(float Aa, float Ab, float Ba, float Bb, float Ca, float Cb); /* Résolution de l'équation */
int PrintComplexe(float a, float b);      /* Affichage d'un nombre complexe */

/* Fonction PRINCIPAL */
int main(void)
{
  char Quite;
  printf("\t\t\t --- Debut du programme ---\n\n");
  do
  {
  
      printf("\n--------------------------------------------------------------------------------");
      /* Lecture des valeurs de l'equation */
      printf("Ax%c+Bx+C=0\n\t",carre);

      printf("A=");
      scanf("%f",&A.za);
      printf("\tA=%f+i",A.za);
      scanf("%f",&A.zb);

      printf("\tB=");
      scanf("%f",&B.za);
      printf("\tB=%f+i",B.za);
      scanf("%f",&B.zb);

      printf("\tC=");
      scanf("%f",&C.za);
      printf("\tC=%f+i",C.za);
      scanf("%f",&C.zb);

      ResEq2Deg(A.za, A.zb, B.za, B.zb, C.za, C.zb);
      printf("\n\t\t\t------------------------------\n");
      
      /* Verification que a != 0 */
      if (  ( (A.za==(float)0) & (A.zb==(float)0) ) & ( (B.za!=(float)0) | (B.zb!=(float)0) )  )
      {
	   /* pour A = 0 et B =! 0, on résout de la maniere suivante: (X = -C / B)*/
           printf("\n( ");
           PrintComplexe(B.za, B.zb);
           printf(" )x + ( ");
           PrintComplexe(C.za, C.zb);
           printf(" ) = 0\n\n=> x = ");
           PrintComplexe(x1.za, x1.zb);
      }

      else if ( (A.za!=(float)0) | (A.zb!=(float)0) )
      {

      /* Affichage du resultat */
		/* Affichage de l'équation */
		printf("\n(");
		PrintComplexe(A.za,A.zb);
		printf(")X%c + (",carre);
		PrintComplexe(B.za,B.zb);
		printf(")X + (");
		PrintComplexe(C.za,C.zb);
		printf(") = 0\n");
		
		/* Résultat */
		
      if (((x1.za!=x2.za) | (x1.zb!=x2.zb)) & ((x2.za!=(float)0) | (x2.zb!=(float)0)) & ((x1.za!=(float)0) | (x1.zb!=(float)0)))
      {
             printf("\n\n\t%c X = ", char(218));
		     PrintComplexe(x1.za,x1.zb);
		     printf("\n=>\t%c\t",char(179));
             printf("ET\n\t%c X = ", char(192));		
		     PrintComplexe(x2.za,x2.zb);
        }
        else if (((x1.za!=x2.za) & (x1.zb!=x2.zb)) & ((x2.za!=(float)0) | (x2.zb!=(float)0)) & (x1.za==(float)0) & (x1.zb==(float)0))
        {
             printf("\n\n=>\t\t X = ");
		     PrintComplexe(x2.za,x2.zb);
        }
        else
        {
             printf("\n\n=>\t\t X = ");
		     PrintComplexe(x1.za,x1.zb);
        }             
        printf("\n");
    }
  
    else printf("Erreur A = B = 0!\n  Resolution Impossible\n"); /* Si a et b sont nul, l'equation ne peut etre resolu */
  
    printf("\n--------------------------------------------------------------------------------");
    printf("\n\n  Appuyez sur q pour quitter ou sur entree pour continuer ...\n\n:");
    scanf("%c",&Quite);
    scanf("%c",&Quite);
  
  } while(Quite!='q');
  printf("\n\n\n\t\t\t --- Fin du programme ---\n\n");
}
/* Fonction ResEq2Deg */
void ResEq2Deg(float a, float b, float c, float d, float e, float f)
{
  /* Variable locale */
  
  float denom, g, h, j, k, l, m, n, o, p;

  
  
  if (  ( (a==(float)0) & (b==(float)0) ) & ( (c!=(float)0) | (d!=(float)0) )  )
  { 
  	/* pour A = 0 et B =! 0, on résout de la maniere suivante: (X = -C / B)*/
    	p = (c*c) + (d*d);
	    x1.za = -( (e * c) + (f * d) ) / p;
	    x1.zb = +( (e * d) + (c * f) ) / p;
    
  }
  else if ((a!=0) | (b!=0))
  {
       /* Calcul du discriminant */
        g = c*c - d*d + 4*(b*f - a*e);
        h = 2*c*d - 4*(a*f + b*e);

        /* Calcul de la racine carré du discriminant */
        j = sqrt( (g + sqrt(g*g + h*h) )/2);
        k = sqrt((sqrt(g*g + h*h) - g)/2);
        if (2*j*k > (float)0 & h<(float)0)
                      k=-k;
        
        /* determination de x1 = (x1.za + i*x1.zb) et x2 = (x2.za + i*x2.zb) */
        p = 2*(a*a + b*b);
  
  
        l = -(a*(+j + c) + b*(k + d))/p;
        m = +(b*(+j + c) - a*(k + d))/p;
        n = +(a*(+j - c) + b*(k - d))/p;
        o = +(b*(-j + c) + a*(k - d))/p;
        x1.za = l;
        x1.zb = m;
        x2.za = n;
        x2.zb = o; 
       
  }
}


int PrintComplexe(float a, float b)
{
     if (a>0) printf("%f",a);
     if (a<0) printf(" - %f",-a);
     if ((b>0)&(b!=1)) printf(" + %fi",b);
     if ((b<0)&(b!=-1)) printf(" - %fi",-b);
     if ((b>0)&(b==1)) printf(" + i");
     if ((b<0)&(b==-1)) printf(" - i");
     if ((a==0)&(b==0)) printf("0");     
}