[C_Algo] 01-01-02 Horner법(다항식계산)

/*
 **********************
 *  호너법  (다항식계산) *
 **********************/
 
 #include <stdio.h>
 
 double fn(double, double *, int);
 
 int main(void)
 {
    // f(x) = 5*x^4 + 4*x^3 + 3*x^2 + 2*x + 1
    static double a[] = { 1, 2, 3, 4, 5};
   
    double x;
   
    for(x = 1; x <= 5; x++)
          printf("fn(%f) = %f\n", x, fn(x, a, 4));
         
    return 0;
}

double fn(double x, double a[], int n)
{
       double p;
       int i;
      
       p = a[n];
      
       for(i = n - 1; i >= 0; i--)
             p = p * x + a[i];
      
       return p;
}