Re: [boost] [test] floating point comparison

Subject: Re: [boost] [test] floating point comparison
From: Raffi Enficiaud (raffi.enficiaud_at_[hidden])
Date: 2015-04-27 17:31:18

Le 26/04/15 22:22, Emil Dotchevski a écrit :
> On Sun, Apr 26, 2015 at 12:14 AM, Gennadiy Rozental <rogeeff_at_[hidden]>
> wrote:
>
>> Emil Dotchevski <emildotchevski <at> gmail.com> writes:
>>
>>>
>>> Hello,
>>>
>>> Can someone please tell me exactly what do I need to include and which
>>> namespace to use to get exact same behavior as:
>>>
>>> #include <boost/test/floating_point_comparison.hpp>
>>>
>>> bool check( float a, float b, float tolerance )
>>> {
>>>      using namespace boost::test_tools;
>>>      return check_is_close(a,b,fraction_tolerance(tolerance));
>>> }
>>>
>>> (The above used to work with older Boost versions but no longer.)
>>
>> Do you refer to the develop branch?
>>
>> BOOST_TEST(a==b, tolerance);
>>
>> should do the same.
>
>
> Yes, sorry -- I mean the development branch.
>
> Could you provide a replacement for the function above? Note that it
> returns a value, which isn't the same as BOOST_TEST. Also please indicate
> what headers need to be included.
>
> Emil
>

Hi Emil,

The corresponding documentation has been updated recently:
http://www.boost.org/doc/libs/develop/libs/test/doc/html/boost_test/users_guide/testing_tools/testing_floating_points.html

and

http://www.boost.org/doc/libs/develop/libs/test/doc/html/boost/math/fpc/close_at_tolerance.html

Those pages indicate the required headers and namespaces.

BOOST_TEST is using this predicate, so would you please give me some 
more info about "Note that it returns a value, which isn't the same as 
BOOST_TEST"?

The corresponding equivalent code should be

bool check( float a, float b, float tolerance )
{
    using namespace boost::math::fpc;
    close_at_tolerance obj(tolerance);
    return obj(a,b);
}

Best,
Raffi