lab8 / main

яю#include "pch.h"

#include <iostream>

#include <math.h>

#include <iomanip>

using namespace std;



double F(double x) {

	return (double)sin(x)/x;

}



double Af(double x) {

	double Pn = (double)5 * x / 2 * (-3 + 7 * x*x);

	double A = 2 / ((1 - x)*(1 - x) * Pn*Pn);

	return A;

}



double gauss(double a, double b) {

	double s = 0, t, t1 = (a + b) / 2, t2 = (b - a) / 2;

	double A[4], X[4];

	X[0] = -0.33998;

	X[1] = 0.33998;

	X[2] = -0.86114;

	X[3] = 0.86114;



	A[0] = Af(X[0]);

	A[1] = Af(X[1]);

	A[2] = Af(X[2]);

	A[3] = Af(X[3]);



	for (int  i = 0; i < 4; i++){

		t = t1 + t2 * X[i];

		s += A[i] * F(t);

	}

	return (t2 * s);

}



int main(){

	

	double I = gauss(1,3);

	cout << "I = " <<fixed <<  setprecision(10)<< I << endl;

}