Re: [Boost-users] A question on the preciseness of the double used in MTL. Can anyone with kindness help me?

Subject: Re: [Boost-users] A question on the preciseness of the double used in MTL. Can anyone with kindness help me?
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-03-28 20:28:13

AMDG

fmingu wrote:
> I am using MTL(Matrix Template Library) for Matrix computing in Dev-C++ 4.9.8.0 and updated the gcc version from 3.2 to 4.4.1 by installing tdm-mingw-1.908.0-4.4.1-2 and the boost version is 1.37.0. The system is Windows xp The sample code is :
>
>  
>
> #include <boost/numeric/mtl/mtl.hpp>
>
>  
>
> #include "boost/random/normal_distribution.hpp"
>
> #include <boost/random.hpp>
>
> #include <boost/random/uniform_real.hpp>
>
>  
>
>  
>
> int main(int argc, char* argv[])
>
> {
>
>     using namespace mtl; using namespace mtl::matrix;
>
>     
>
>     const unsigned n= 5;
>
>     dense2D<double>                            A(n, n), B(n, n);
>
>     morton_dense<double, doppled_64_row_mask>  C(n, n), D(n, n);
>
>     
>
>     dense2D<double>                            F(n, n), E(n, n);
>
>     hessian_setup(A, 3.0); hessian_setup(B, 1.0); 
>
> hessian_setup(C, 2.0); hessian_setup(D, 11.0);
>
> B(1,1)=9.9999;
>
> ..........................
>
>     std::cout << "The matrices are: B=\n" << B <<"\n"; 
>
>     std::cout << "The result is  " <<1.0/3.0 <<"\n";
>
> ¡­¡­¡­¡­¡­¡­¡­¡­.
>
> But the result is shown that B(1,1) is 10, and 1.0/3.0 is 0.33.
>
> How can I get the highest precision of the type double and dense2D<double> for scientific computation?
>
> The same question occurred in random number generation in boost random library.
>   

Use std::setprecision to print more digits.

In Christ,
Steven Watanabe