Re: [Boost-users] [fusion][mpl::math] generic math operations

From: Cromwell Enage (sponage_at_[hidden])
Date: 2007-01-24 09:12:30

--- Michael Marcin wrote:
> I hadn't heard of MPL.Math before...
> 
> I was actually looking for a way the other day of
> computing a fixed-point sin lookup table at
> compile-time using Taylor series approximation for
> a fixed-point class I have templated on magnitude
> and fractional bit count.  I ended up getting lost
> and wrote a small program to generate a table and
> copy & pasted the output into a source file for 
> the fixed-point precision I was using at present.
> 
> It seems that it would be nice to be able to
> generate a new table for say 8.24 fixed-point
> without needed to rerun an external tool.

#include <iostream>
#include <boost/mpl/math/double.hpp>
#include <boost/mpl/math/sine.hpp>
#include <boost/mpl/runtime_cast.hpp>

using namespace boost;
using namespace mpl;
using namespace math;

int main()
{
    sine<string_c_to_double<8,'.',2,4> >::type
        your_answer;

    // The runtime_cast function template
    // converts the internal representation
    // to the template argument type
    // for readability.
    std::cout
     << runtime_cast<double>(your_answer)
     << std::endl;

    return 0;
}

> Does this seem like the sort of thing MPL.Math
> could help with?

You can look at the sine.cpp example program and see
for yourself.  As for the sine metafunction
implementation, the Taylor series is actually built
using a combination of Boost.Preprocessor macros and
intermediary typedefs instead of template recursion.

> Thanks,

No problem.

> Michael Marcin

                              Cromwell D. Enage

 
____________________________________________________________________________________
Never miss an email again!
Yahoo! Toolbar alerts you the instant new Mail arrives.
http://tools.search.yahoo.com/toolbar/features/mail/