machine eps related query

1 view (last 30 days)
Sean Doherty
Sean Doherty on 29 Dec 2020
Answered: Ameer Hamza on 29 Dec 2020
1 + eps > 1
ans =
logical
1
% as expcted
1 + eps
ans =
1.000000000000000
% unexpected, and indeed
1+2.5*eps
ans =
1.000000000000000
any help appreciated

Accepted Answer

Ameer Hamza
Ameer Hamza on 29 Dec 2020
It happens because of finite precision of double() precision datatype: https://en.wikipedia.org/wiki/Double-precision_floating-point_format. Also, because of the fact that MATLAB only prints 16 digits by default, the remaining digits after conversion are not shown (double datatype cannot store more than 16 digits accurately). Try the following
>> fprintf('%0.20f\n', 1+eps)
1.00000000000000022204
>> fprintf('%0.20f\n', 1+2.5*eps)
1.00000000000000044409

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by