Re: [Boost-users] multiprecision modf

Subject: Re: [Boost-users] multiprecision modf
From: John Maddock (jz.maddock_at_[hidden])
Date: 2016-08-03 07:52:27

On 03/08/2016 06:36, Daniel Brake wrote:
> Hi Boost,
>
> Does Boost.Multiprecision provide modf for floating point types?  I 
> need it for generating with Karma, unless the fact that mpfr_float 
> with variable precision not having numeric_traits might get in the way.

No it doesn't, and I'm not sure how/why we missed that one.

A quick and dirty workaround would be something like:

template <class T>
T modf(T val, T* ipart)
{
     *ipart = boost::math::trunc(val);
     return val - *ipart;
}

Meanwhile I guess I'd better go off and implement it properly....

John.

>
> Thanks for any help.  Error message follows.
>
> In file included from test/generating/mpfr_float.cpp:27:
> In file included from ./include/bertini2/io/generators.hpp:38:
> In file included from 
> /usr/local/include/boost/spirit/include/karma.hpp:16:
> In file included from /usr/local/include/boost/spirit/home/karma.hpp:15:
> In file included from 
> /usr/local/include/boost/spirit/home/karma/numeric.hpp:16:
> In file included from 
> /usr/local/include/boost/spirit/home/karma/numeric/real.hpp:32:
> In file included from 
> /usr/local/include/boost/spirit/home/karma/numeric/real_policies.hpp:21:
> /usr/local/include/boost/spirit/home/karma/numeric/detail/real_utils.hpp:115:33: 
> error: no matching function for call to 'modf'
>             U fractional_part = modf(n, &integer_part);
>                   ^~~~
> /usr/local/include/boost/spirit/home/karma/numeric/real_policies.hpp:94:30: 
> note: in instantiation of function template specialization
> 'boost::spirit::karma::real_inserter<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >, 
> boost::spirit::unused_type,
> boost::spirit::unused_type>::call_n<boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> >,
> mpl_::int_<0>, boost::spirit::unused_type>, 
> boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >' requested 
> here
> return Inserter::call_n(sink, n, p);
>                ^
> /usr/local/include/boost/spirit/home/karma/numeric/detail/real_utils.hpp:56:31: 
> note: in instantiation of function template specialization
> 'boost::spirit::karma::real_policies<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>
> >::call<boost::spirit::karma::real_inserter<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >, 
> boost::spirit::unused_type, boost::spirit::unused_type>,
> boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> >, mpl_::int_<0>,
> boost::spirit::unused_type>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> > >' 
> requested here
> return p.template call<real_inserter>(sink, n, p);
>                 ^
> /usr/local/include/boost/spirit/home/karma/numeric/real.hpp:192:35: 
> note: in instantiation of function template specialization
> 'boost::spirit::karma::real_inserter<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >, 
> boost::spirit::unused_type,
> boost::spirit::unused_type>::call<boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> >,
> mpl_::int_<0>, boost::spirit::unused_type>, 
> boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >' requested 
> here
> return inserter_type::call(sink, traits::extract_from<T>(attr, 
> context), p_) &&
>                     ^
> /usr/local/include/boost/spirit/home/karma/generate.hpp:69:45: note: 
> in instantiation of function template specialization
> 'boost::spirit::karma::any_real_generator<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >, 
> boost::spirit::unused_type,
> boost::spirit::unused_type>::generate<boost::spirit::karma::detail::output_iterator<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> >,
> mpl_::int_<0>, boost::spirit::unused_type>, 
> boost::spirit::context<boost::fusion::cons<const
> boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> &, 
> boost::fusion::nil_>, boost::spirit::locals<mpl_::na, mpl_::na, 
> mpl_::na, mpl_::na,
> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na> >, 
> boost::spirit::unused_type,
> boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> >' requested 
> here
>         return compile<karma::domain>(expr).generate(sink, context, 
> unused, attr);
>                               ^
> /usr/local/include/boost/spirit/home/karma/generate.hpp:91:23: note: 
> in instantiation of function template specialization
> 'boost::spirit::karma::generate<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> >, mpl_::int_<0>,
> boost::spirit::karma::real_generator<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> > >, 
> boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0,
> allocate_dynamic>, 
> boost::multiprecision::expression_template_option::et_on> >' requested 
> here
>         return karma::generate(sink, expr, attr);
>         ^
> ./include/bertini2/io/generators.hpp:149:21: note: in instantiation of 
> function template specialization
> 'boost::spirit::karma::generate<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> >,
> boost::spirit::karma::real_generator<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>,
> bertini::generators::BertiniNumPolicy<boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on> > >, 
> boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0,
> allocate_dynamic>, 
> boost::multiprecision::expression_template_option::et_on> >' requested 
> here
>       return generate(sink,
>              ^
> test/generating/mpfr_float.cpp:53:47: note: in instantiation of 
> function template specialization
> 'bertini::generators::Classic::generate<std::__1::back_insert_iterator<std::__1::basic_string<char> 
> > >' requested here
> BOOST_CHECK(bertini::generators::Classic::generate(sink, z));
>                                 ^
> /usr/include/math.h:407:15: note: candidate function not viable: no 
> known conversion from
> 'boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>' to 'double' 
> for 1st argument
> extern double modf(double, double *);
> ^
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:940:46: 
> note: candidate function not
>       viable: no known conversion from 
> 'boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>' to 'float' 
> for 1st argument
> inline _LIBCPP_INLINE_VISIBILITY float       modf(float __lcpp_x, 
> float* __lcpp_y) _NOEXCEPT             {return modff(__lcpp_x, __lcpp_y);}
>                                ^
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:941:46: 
> note: candidate function not
>       viable: no known conversion from 
> 'boost::multiprecision::number<boost::multiprecision::backends::mpfr_float_backend<0, 
> allocate_dynamic>,
> boost::multiprecision::expression_template_option::et_on>' to 'long 
> double' for 1st argument
> inline _LIBCPP_INLINE_VISIBILITY long double modf(long double 
> __lcpp_x, long double* __lcpp_y) _NOEXCEPT {return modfl(__lcpp_x, 
> __lcpp_y);}
>
> Daniel Brake
>
>
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users