Re: [Boost-users] First attempt at using Boost::Test is a flop: the program ends with an exception related to std::string but I don't use any

Subject: Re: [Boost-users] First attempt at using Boost::Test is a flop: the program ends with an exception related to std::string but I don't use any
From: Oswin Krause (Oswin.Krause_at_[hidden])
Date: 2012-05-23 04:29:23

Hi,

> I also hit a limitation of    BOOST_CHECK_CLOSE.  In testing my code 
> to
> check the accuracy of the algorithm for the standard normalized 
> normal
> distribution, of zero mean and unit variance, it always failed, 
> giving an
> infinite percent accuracy.  Changing the distribution to mean of one 
> and
> variance of one resulted in the test passing.  Clearly the incorrect 
> result
> of a failed test was due to a division by zero, and thus 
> BOOST_CHECK_CLOSE
> clearly can not compare a double with 0.0, and that strikes me as a
> significant limitation.  It is true that for my purposes, simply 
> shifting
> the distribution to the right by one meets my needs, I can imagine 
> cases in
> which that is not viable.  Is there another macro that is specialized 
> for
> the case when the expected outcome, for a double, of a given 
> calculation is
> zero?

BOOST_CHECK_CLOSE can't work, because it evaluates a difference between 
the two values in percent. But  no one can answer how many percent 
difference are between 0 and 1 (I think infinite is a good guess, 
though). What you are searching is BOOST_CHECK_SMALL which checks, 
whether a number is smaller than a certain threshold.

Greetings,
Oswin