Re: [Boost-users] Questions about Boost multiprecision library.

Subject: Re: [Boost-users] Questions about Boost multiprecision library.
From: John Maddock (jz.maddock_at_[hidden])
Date: 2018-10-10 17:22:11

> *I have heard that there are some strange results that
> can happen if you are quizzing multiprecision for trigonometry
> and try to keep using the double type.  Is this true,
> so that I can just kee relying on the std library instead?
>

Sorry don't understand the question.

> -What is the name of the 64 bit windows .dll, or .dll files,
> that are the ones for the multiprecision library?
>

There are none - it's header only.

> -If I wish to go into arbitrary precision and scale numbers,
> what is the type I should use for an *integer*?  What is the
> #include statement I should use, and how do I specify
> the number of whole number points and decimal points,
> before starting my operations?

What kind of integer?  Fixed precision or arbitrary precision?

Suggest you start with:

#include <boost/multiprecision/cpp_int.hpp>

using boost::multiprecision::int1024_t;   // fixed precision 1024-bit 
integer, or:
using boost::multiprecision::cpp_int;    // arbitrary precision integer

See 
https://www.boost.org/doc/libs/1_66_0/libs/multiprecision/doc/html/boost_multiprecision/tut/ints/cpp_int.html 
for other typedefs and examples.

 >and how do I specify the number of whole number points and decimal 
points,before starting my operations?

That question makes no sense for integer types.

>
> -If I wish to go into arbitrary precision and scale numbers,
> what is the type I should use for a *rational number*? What
> is the #include statement I should use, and how do I specify
> the number of whole number points and decimal points,
> before starting my operations?

If you want arbitrary precision then try:

#include <boost/multiprecision/cpp_int.hpp>

using boost::multiprecision::cpp_rational;    // arbitrary precision 
rational

or:

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

using boost::multiprecision::int1024_t;   // fixed precision 1024-bit 
integer, or:
typedef boost::rational<int1024> rational_1024_t;  // 1024 bit fixed 
precision rational

As before your other questions make no sense for these types.

See 
https://www.boost.org/doc/libs/1_66_0/libs/multiprecision/doc/html/boost_multiprecision/tut/rational/cpp_rational.html

>
> -For these two types, I wish to do sine, cosine, tangent,
> arcsine, arccosine, arctangent, base 10 logarithm,
> base e logarithm, power, nth root.  I also want
> to obtain pi, but also Euler's constant, to any number
> of significang figure or decimal places that I would like.

Really??? Eulers constant as an integer?  I think you need to re-think 
that question.

Best, John.

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus