Re: [Boost-users] Cpp_int and cpp_dec_float conversion

Subject: Re: [Boost-users] Cpp_int and cpp_dec_float conversion
From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2013-04-23 11:53:58

From: Boost-users [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Alessandro Tagliapietra
Sent: Monday, April 22, 2013 5:19 PM
To: boost-users_at_[hidden]
Subject: [Boost-users] Cpp_int and cpp_dec_float conversion
 
Hello,
 
is there a way to convert from cpp_int to cpp_dec_float and viceversa?
 
Since I've to use the modulus between two cpp_dec_float which I know they're integers but I need
sqrt before and trying to run % with them gives:
 
/usr/local/include/boost/multiprecision/number.hpp: In member function 'void
boost::multiprecision::number<Backend, ExpressionTemplates>::do_assign(const Exp&, const
boost::multiprecision::detail::modulus_immediates&) [with Exp =
boost::multiprecision::detail::expression<boost::multiprecision::detail::modulus_immediates,
boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
et_on>, boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, int,
void>, et_on>, void, void>, Backend = boost::multiprecision::backends::cpp_dec_float<100u, int,
void>, boost::multiprecision::expression_template_option ExpressionTemplates = et_on]':
/usr/local/include/boost/multiprecision/number.hpp:680:   instantiated from 'void
boost::multiprecision::number<Backend, ExpressionTemplates>::do_assign(const
boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, Arg4>&, const mpl_::true_&) [with
tag = boost::multiprecision::detail::modulus_immediates, Arg1 =
boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
et_on>, Arg2 = boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u,
int, void>, et_on>, Arg3 = void, Arg4 = void, Backend =
boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
boost::multiprecision::expression_template_option ExpressionTemplates = et_on]'
/usr/local/include/boost/multiprecision/number.hpp:134:   instantiated from 'typename
boost::enable_if<boost::is_convertible<typename boost::multiprecision::detail::expression<tag, Arg1,
Arg2, Arg3, Arg4>::result_type, boost::multiprecision::number<Backend, ExpressionTemplates> >,
boost::multiprecision::number<Backend, ExpressionTemplates>&>::type
boost::multiprecision::number<Backend, ExpressionTemplates>::operator=(const
boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, Arg4>&) [with tag =
boost::multiprecision::detail::modulus_immediates, Arg1 =
boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
et_on>, Arg2 = boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u,
int, void>, et_on>, Arg3 = void, Arg4 = void, Backend =
boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
boost::multiprecision::expression_template_option ExpressionTemplates = et_on]'
/usr/local/include/boost/multiprecision/number.hpp:181:   instantiated from
'boost::multiprecision::number<Backend, ExpressionTemplates>::number(const
boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, Arg4>&, typename
boost::enable_if_c<boost::is_convertible<typename boost::multiprecision::detail::expression<tag,
Arg1, Arg2, Arg3, Arg4>::result_type,boost::multiprecision::number<Backend, ExpressionTemplates>
>::value, void>::type*) [with tag = boost::multiprecision::detail::modulus_immediates, Arg1 =
boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
et_on>, Arg2 = boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u,
int, void>, et_on>, Arg3 = void, Arg4 = void, Backend =
boost::multiprecision::backends::cpp_dec_float<100u, int, void>,
boost::multiprecision::expression_template_option ExpressionTemplates = et_on]'
test.cpp:20:   instantiated from here
/usr/local/include/boost/multiprecision/number.hpp:912: error: invalid application of 'sizeof' to
incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>'
 
 
 
I'm sure John Maddock will give a fully informed reply to this, but this
 
boost::multiprecision::expression_template_option ExpressionTemplates = et_on
 
suggests that you might try setting the 'use  expression templates' template parameter to NOT use ET
 
boost::multiprecision::expression_template_option ExpressionTemplates = et_off
 
HTH
 
Paul
 
 
---
Paul A. Bristow,
Prizet Farmhouse, Kendal LA8 8AB  UK
[phone]  07714330204
pbristow_at_[hidden]