poly.c

#include<stdio.h>
#include<stdlib.h>

double f(double c3,double c2,double c1,double c0,double x){
	double f = c3*x*x*x + c2*x*x + c1*x + c0;
	return f;
}

int main(){
	char *poly = "C3*x^3 + C2*x^2 + C1*x + C0";
	double x, c3,c2,c1,c0, *val;
	double x1,x2, max, min;
	int num,i;
	double mxpos,mnpos;
	mxpos = mnpos = 0.0;
	printf("For the polynomial %s, enter the value of C3,C2,C1 and C0: ",poly);
	scanf("%lf %lf %lf %lf",&c3,&c2,&c1,&c0);
	printf("Enter range of x(x1 to x2): ");
	scanf("%lf %lf",&x1,&x2);
	num = (int)((x2-x1)/0.1)+1;
	val = (double*)(malloc(sizeof(double)*num));
	for(i=0;i<num;i++){
		val[i] = f(c3,c2,c1,c0,x1+0.1*i);
		if(i==0){
			max = val[0];
			min = val[0];
			continue;
		}
		if(val[i]>max){
			max = val[i];
			mxpos = x1+0.1*i;
		}
		if(val[i]<min){
			min = val[i];
			mnpos = x1+0.1*i;
		}
	}
	printf("Largest value of f(x): %lf at %lf\n", max,mxpos);
	printf("Smallest value of f(x): %lf at %lf\n", min,mnpos);
	return 0;
}