Newton Raphson

       //New-Raps

#include <stdio.h>
#include <conio.h>
#include <math.h>

#define N 16

typedef unsigned char LOGIC;
LOGIC Newton_Rapson(int,float [],float,float,float *,int);
float Valpol(int,float [],float);
float Derpol(int,float [],float);

int main(void)
{
  int n=2;              // gradul polinomului
  float A[]={-6,-1,1};  // vectorul coeficientilor polinomului
  float x0=7;           // punctul de start
  float er=0.0001;      // precizia de calcul a radacinii
  float rad;

  if(Newton_Rapson(n,A,x0,er,&rad,N)) printf("\nSolutia este : %f",rad);
  else printf("\nEroare");

  getch();
  return 1;
}
LOGIC Newton_Rapson(int n,float A[],float x0,float er,float *pRad,int nmax)
{
   float xn,xn_1;

   xn=x0;
   do{
      xn_1=xn;
      if(Derpol(n,A,xn_1)==0) { return(0);}
      xn=xn_1-(Valpol(n,A,xn_1)/Derpol(n,A,xn_1));
      nmax=nmax-1;
      } while(fabs(xn-xn_1)>=er && nmax!=0);

   *pRad=xn;
   return(1);
}

float Valpol(int n,float A[],float pc)
{
  int i;
  float b;

  b=A[n];
  for(i=n-1;i>=0;i--) b=A[i]+pc*b;

  return b;
}

float Derpol(int n,float A[],float pc)
{
  int i;
  float b[N];
  float c;

  b[n]=A[n];
  c=b[n];
  for(i=n-1;i>=1;i--)
  {
   b[i]=A[i]+pc*b[i+1];
   c=b[i]+pc*c;
   }
  return c;
}