C++ Boost multiprecision cpp_int

Question

我尝试获取大数的日志。我应该怎么做？因为它说Cannot open include file: 'gmp.h': No such file or directory

下面的代码，我不能使用gmp.hpp

#include <iostream> 
#include <boost/multiprecision/cpp_int.hpp> 

#define rsa100 "1522605027922533360535618378132637429718068114961380688657908494580122963258952897654000350692006139" 


using namespace std; 
using namespace boost::multiprecision; 

int main(){ 
    cpp_int n(rsa100); 
    cout << boost::multiprecision::log(n); 
    return 0; 
} 

给我的错误：

1>------ Build started: Project: rsa, Configuration: Debug x64 ------ 
1> Source.cpp 
1>Source.cpp(12): error C2893: Failed to specialize function template 'enable_if_c<boost::multiprecision::number_category<Num>::value==1,boost::multiprecision::detail::expression<boost::multiprecision::detail::function,boost::multiprecision::detail::log_funct<Backend>,boost::multiprecision::number<B,et_on>,void,void>>::type boost::multiprecision::log(const boost::multiprecision::number<B,et_on> &)' 
1>   With the following template arguments: 
1>   'Backend=boost::multiprecision::backends::cpp_int_backend<0,0,signed_magnitude,unchecked,std::allocator<boost::multiprecision::limb_type>>' 
1>Source.cpp(12): error C2784: 'enable_if_c<boost::multiprecision::number_category<boost::multiprecision::detail::expression<tag,Arg1,Arg2,Arg3,Arg4>>::value==number_kind_floating_point,boost::multiprecision::detail::expression<boost::multiprecision::detail::function,boost::multiprecision::detail::log_funct<detail::backend_type<boost::multiprecision::detail::expression<tag,Arg1,Arg2,Arg3,Arg4>>::type>,boost::multiprecision::detail::expression<tag,Arg1,Arg2,Arg3,Arg4>,void,void>>::type boost::multiprecision::log(const boost::multiprecision::detail::expression<tag,Arg1,Arg2,Arg3,Arg4> &)' : could not deduce template argument for 'const boost::multiprecision::detail::expression<tag,Arg1,Arg2,Arg3,Arg4> &' from 'boost::multiprecision::cpp_int' 
1>   C:\boost_1_55_0\boost/multiprecision/detail/default_ops.hpp(1998) : see declaration of 'boost::multiprecision::log' 
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== 

Answer 1

log需要一个实数，而不是整数。

#include <iostream> 
#include <iomanip> 
#include <boost/multiprecision/cpp_dec_float.hpp> 

#define rsa100 "1522605027922533360535618378132637429718068114961380688657908494580122963258952897654000350692006139" 

using namespace std; 
using namespace boost::multiprecision; 

int main(){ 
    cpp_dec_float_100 n(rsa100); 

    auto log_n  = log(n); 
    auto exp_log_n = exp(log_n); 

    cout << std::fixed << log_n  << "\n"; 
    cout << std::fixed << exp_log_n << "\n"; 
} 

看到它Live on Coliru