/*

一維多項求解

p(x)=2x^6-5x^5+3x^4+x^3-7x^2+7x-20

*/

  #include <stdio.h>

  double plyv(double a[],int n,double x)

  { int i;

    double u;

    u=a[n-1];

    for (i=n-2; i>=0; i--)

      u=u*x+a[i];

    return(u);

  }

  void main(void)

  { int i;

    staticdouble a[7]={-20.0,7.0,-7.0,1.0,3.0,-5.0,2.0};

    staticdouble x[6]={0.9,-0.9,1.1,-1.1,1.3,-1.3};

    printf("\n");

    for (i=0; i<=5; i++)

      printf("x(%d)=%5.2lf   p(%d)=%13.7e\n",

             i,x[i],i,plyv(a,7,x[i]));

    printf("\n");

  }