C PROGRAM FOR SIMPSON'S 1/3rd RULE OF NUMERICAL INTEGRATION

/*PROGRAM FOR SIMPSON'S 1/3rd RULE OF NUMERICAL INTEGRATION*/

#include<stdio.h>
#include<conio.h>
#include<math.h>
#define f(X)  (4*X-(3*(X*X)))
void main() {
int i,n;
float a,b,h,x[20],y[20],j;
clrscr();
printf("Enter upper limit,lower limit & sub interval:");
scanf("%f %f %d",&a,&b,&n);
x[0]=b;
h=(a-b)/n;
for(i=0;i<=n;i++) {
      y[i]=f(x[i]);
      x[i+1]=x[i] + h;
}
j=y[0];
for(i=0;i<=n-2;i+=2)
j=j + ((h/3) * (y[i]+4*y[i+1]+y[i+2]));
printf("The required value is=%f ", j);
getch();
}

/*OUTPUT:-
Enter upper limit,lower limit & sub interval:1
0
10
The required value is=1.000000  */