c program of simpson's 1/3 rule.

Implementation of Simpson’s 1/3 Rule.

#include<stdio.h>

#include<conio.h>

#include<math.h>

#include<process.h>

#include<string.h>

float fun(float);

void main()

{

  float result=1;

  float a,b;

  float h,sum;

  int i,j;

  int n;

  clrscr();

  printf("\n\n Enter the range-");

  printf("\n\n Lower Limit a-");

  scanf("%f",&a);

  printf("\n\n Lower Limit b-");

  scanf("%f",&b);

  printf("\n\n Enter number of subintervals -");

  scanf("%d",&n);

  h=(b-a)/n;

  sum=0;

  sum=fun(a)+4*fun(a+h)+fun(b);

  for(i=3;i<n;i++)

  {

    sum+=fun(a+(i-1)*h)+4*fun(a+i*h);

  }

  result=sum*h/3;

  printf("\n\n\n\n Value of the integral is %6.4f\t",result);

  printf("\n\n\n Press Enter to Exit");

  getch();

  }

  float fun(float x)

  {

    float temp;

    temp=1/(1+(x*x));

    return temp;

 }