Re: [Boost-users] [test] CLOSE and CLOSE_FRACTION tolerance

Subject: Re: [Boost-users] [test] CLOSE and CLOSE_FRACTION tolerance
From: Gennadiy Rozental (rogeeff_at_[hidden])
Date: 2011-06-03 01:55:11

Edward Diener <eldiener <at> tropicsoft.com> writes:

> 
> I am trying to understand the tolerance value passed as the last 
> parameter to the BOOST_XXX_CLOSE and BOOST_XXX_CLOSE_FRACTION macros. 
> The doc says that for the former the value is percentage units while for 
> the latter it is the fraction of absolute values being compared. But in 
> each case there are two values, not just one. Which of the two values 
> are used to determine the tolerance amount in each case ? If both values 
> are being used in each case, how is the tolerance amount computed from 
> the tolerance value passed ?

These are using strict check:

|a-b|/|a| < tolerance
and
|a-b|/|b| < tolerance

You can get weak check if you want (or instead of and above) by using
close_at_tolerance predicate directly.

Regards
Gennadiy