Re: [Boost-users] lambda : fabs( x - y )< eps

Subject: Re: [Boost-users] lambda : fabs( x - y )< eps
From: Thomas Heller (thom.heller_at_[hidden])
Date: 2011-03-12 06:51:30

On Fri, Mar 11, 2011 at 5:14 AM, Steven Watanabe <watanabesj_at_[hidden]> wrote:
> AMDG
>
> On 03/10/2011 04:40 PM, er wrote:
>>
>> I'm submitting this in case someone easily spots a less verbose
>> representation of fabs( x - y )< eps than the one shown below and would like
>> to share it. Using lambda (or variants) only (I know I can write my own
>> functor class). Thanks.
>
> How about using the attached cmath.hpp for phoenix?
>
> #include <cmath>
> #include <boost/function.hpp>
> #include <boost/lambda/bind.hpp>
> #include <boost/lambda/lambda.hpp>
> #include <boost/phoenix/core.hpp>
> #include <boost/phoenix/operator.hpp>
> #include "cmath.hpp"
>
> int main() {
> double eps = 0.000001;
> using namespace boost::phoenix::arg_names;
> boost::function<bool(double, double)> f = fabs(_1 - _2) < eps;
>
> BOOST_ASSERT( f( 0.0, 0 * eps ) );
> BOOST_ASSERT( !f( 0.0, eps ) );
> }
>
> In Christ,
> Steven Watanabe

Thanks! This is a nice and welcome contribution!
I just committed it under the "stdlib" subdirectory.

Thanks,
Thomas