Unit 4.1 Trapezoidal Integration

#include <stdio.h>
#include <math.h>
#define f(x) (sin(x)-log(x)+exp(x)) //1.4 0.2 0.1
// #define f(x) x*x*x*x //3 -3 1

int main()
{
    float b,a,h,x[20],sum=0;
    int n;
    printf("Enter the values of upper limit,lower limit and h\n");
    scanf("%f %f %f",&b,&a,&h);

    n = ceil(((b-a)/h));

    for(int i=0 ; i<=n ; i++){
        x[i] = a+ (i*h);
    }
    for(int i=1 ; i<n ; i++){
        sum += f(x[i]);
    }

    float ans = (h/2) * ( f(x[0]) + f(x[n]) + (2*sum) ) ;
    printf ("\nFinal answer is %f",ans);

    return 0;
}
/*
Output 1
Enter the values of upper limit,lower limit and h
1.4 .2 .1

Final answer is 4.056173

Output 2
Enter the values of upper limit,lower limit and h
3 -3 1
Final answer is 115.000000
*/



Algo

define function
read a,b and h , where a lower , b upper limit and h size of interval
n = (b-a)/h + 1
declare float array x of size of n

start a loop from i=0 to n-1
    x[i] = a + (i*h)
end i loop

calulate sum of all ordinates excluding extreme
declare sum = 0
    start loop from i=1 to n-2
        sum = sum + f(x[i])
    end loop i

ans = h/2 * ( f(x[0]) + f(x[n-1]) + (2*sum)

print ans
stop