math5610

Routine Name: getDoubleMachineEpsilon

Author: Andrew Aposhian

Language: C++

To use this function, include the correct header file at the top of your file as follows:

#include "MachineEpsilon.hpp"

Description/Purpose: Find the smallest positive number (or machine epsilon) that your computer and compiler is capable of storing using double precision float.

Input: No parameters

Output: Double precision machine epsilon as a double

Usage/Example: This example shows calling the function and assigning the return value to the variable epsilon:

double epsilon = getDoubleMachineEpsilon();
std::cout << epsilon << std::endl;

Output from lines above:

4.94066e-324

Implementation/Code: See MachineEpsilon.cpp on GitHub

double getDoubleMachineEpsilon() {
    double epsilon = 1;
    double nextPossibleEpsilon = epsilon;
    while (nextPossibleEpsilon > 0) {
        epsilon = nextPossibleEpsilon;
        nextPossibleEpsilon /= 2;
    }
    return epsilon;
}

Last Modified: January/2019