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

double p[5]={3,-2,1,-5,1};
double a=2;

typedef struct { double y, dy; } sydy;

sydy peval(double a, int n, double p[]){
    double y=p[0], dy=p[0];
    for(int i=1;i<n;i++){
        y=a*y+p[i];
        if(i<n-1) dy=a*dy+y;
    }
    sydy answer;
    answer.y=y;
    answer.dy=dy;
    return answer;
}

double newton(double x){
    sydy answer=peval(x,sizeof(p)/sizeof(double),p);
    return x-answer.y/answer.dy;
}

int main(){
    double x=0;
    for(int i=1;i<10;i++){
        x=newton(x);
        printf("x_%d = %.15g\n",i,x);
    }
    return 0;
}