Trapezoidal

#include<stdio.h>

float y(float x)
{
	return 1/(1+x*x);
}

// Function to evaluate the value of integral
float trapezoidal(float a, float b, float n)
{
	float h = (b-a)/n;

	// Computing sum of first and last terms in above formula
	float s = y(a)+y(b);
	printf("\n%f\n", (h/2)*s);

	// Adding middle terms in above formula
	for (int i = 1; i < n; i++)
	{
		s += 2*y(a+i*h);
		printf("%f\n", (h/2)*s);
	}

	// h/2 indicates (b-a)/2n. Multiplying h/2
	// with s.
	return (h/2)*s;
}

int main()
{
	float x0, xn;   // Range of definite integral
	int n;  // Number of grids. Higher value means more accuracy
        printf("Enter the range of definite integral: ");
        scanf("%f %f", &x0, &xn);

	printf("Enter the number of grids: ");
        scanf("%d", &n);

	printf("\nValue of integral is %6.4f\n", trapezoidal(x0, xn, n));
	return 0;
}