Integral.c

#include <stdio.h>
#include <math.h>

typedef double (*function)(double);

double func(double);
double integral(function, double, double);

const int SECTIONS_QUANTITY = 1e4;
// const double EPS = 1e-6;

int main(int argc, char const *argv[])
{
	printf(
		"computed integral sinxdx from 0 to 2Pi = %.6f\nand must be 0",
		integral(&sin, 0.0, 3 * M_PI)
	);

	
	printf(
		"computed integral polynome dx from 0 to 15 = %.6f\nand must be ...",
		integral(&polynome, 0.0, 15.0)
	);

	return 0;
}

double integral(function f, double from, double to)
{
    const double STEP = (double) (to - from) / SECTIONS_QUANTITY;
    double s = 0.0;

    for (double x = from; x < to; x += STEP)
    {
    	s += f(x) * STEP;
    }

    return s;
}

double polynome(double x)
{
    return x * x - 13 * x + 36;
}