Rounding numbers in C ++

Faced such a problem that VS in C ++ rounds the numbers that it gets after all the calculations. I don't need this. How to make it give accuracy up to 10 ^ -14? Because the errors are about there. I used float for all numbers. Then I tried double. there was no difference.

#include "stdafx.h" #include <iostream> #include <fstream> using namespace std; int main() { ifstream fmatrix("C:\\Users\\Pavel\\Desktop\\cpp1\\matrix.txt"); ifstream ffree("C:\\Users\\Pavel\\Desktop\\cpp1\\free.txt"); double matrix[30][30]; double matrixCopy[30][30]; double free[30]; double x[30]; double freeNew[30]; for (int i = 0; i < 30; i++) for (int j = 0; j < 30; j++) fmatrix >> matrix[i][j]; for (int i = 0; i < 30; i++) for (int j = 0; j < 30; j++) matrixCopy[i][j]=matrix[i][j]; for (int i = 0; i < 30; i++) ffree >> free[i]; for (int k = 0; k < 29; k++) //Прямой ход Гаусса { for (int j = k + 1; j < 30; j++) { double r = matrix[j][k] / matrix[k][k]; for (int i = k; i < 30; i++) matrix[j][i] -= matrix[k][i] * r; free[j] -= free[k] * r; } } for (int i = 0; i < 30; i++) x[i] = 0; for (int k = 29; k >= 0; k--)//Обратный ход Гаусса { double r = 0; for (int j = k + 1; j < 30; j++) { double g = matrix[k][j] * x[j]; r += g; } x[k] = (free[k]-r) / matrix[k][k];; } for (int i = 0; i < 30; i++) freeNew[i] = 0; for (int i = 0; i < 30; i++) for (int j = 0; j < 30; j++) freeNew[i] += matrixCopy[i][j] * x[j]; for (int i = 0; i < 30; i++) cout << freeNew[i] << endl; system("pause"); return 0; }