Programming for integration by simpson's 1/3 rule

/*integration by simpson's 1/3 rule*/

#include<stdio.h>

#include<math.h>

float f(float x)

{

float d;

d=(x/(1+pow(x,5)));

return d;

}

void

main()

{

int i,n;

float a,b,h,s=0.0,c;

printf("enter the value of lower and upper limit:");

scanf("%f %f",&a,&b);

printf("enter the number of intervals:");

scanf("%d",&n);

label:

h=(b-a)/n;

c=s;

s=f(a)+f(b)+4*f(a+h);

for(i=3;i<=(n-1);i=i+2)

{

                s=s+(4*f(a+i*h))+(2*f(a+(i-1)*h));

}

s=(h/3.0)*s;

if(fabs (s-c)/s>0.001)

{

                n=n+10;

                goto label;

}

printf("the value of the interval is %.3f and is converged %d intervals\n",s,n);

}

RESULT:

enter the value of lower and upper limit:0 3

enter the number of intervals:10

the value of the interval is 0.648 and is converged 20 intervals

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