Re: [Boost-users] BOOST_CHECK_CLOSE with integral types

From: Gennadiy Rozental (gennadiy.rozental_at_[hidden])
Date: 2005-09-21 09:59:18

"Will Bryant" <will_at_[hidden]> wrote in message 
news:4331173C.7060405_at_core-dev.co.nz...
> Hi all,
>
> Is BOOST_CHECK_CLOSE supposed to work with integral types?  I find that
> if I try:
>
>        long var1 = 1001;
>        BOOST_CHECK_CLOSE(var1, 2000L, 10L);
>
> under both MSVC 2005 and GCC 3.4, it'll pass, which is wrong as far as I
> can see - whereas:
>
>        double var2 = 1001.0;
>        BOOST_CHECK_CLOSE(var2, 2000.0, 10.0);
>
> fails as it should.
>
> Why is this?  int has the same problem.

BOOST_CHECK_CLOSE algorithm involves division (it compared relative distance 
with tolerance). |a-b|/|a| will always produce 0 for integral types. Which 
is less then any tolerance you could specify.

Gennadiy