math::round broken for some integer types/values

[andrew.bell.ia@…]

The current code takes the input (which may be an int type) and adds/subtracts .5f, which may cause precision to be lost as the integer is converted to a float. math::round should essentially be a noop when the input type is integral.

===========

#include <iostream>
#include <iomanip>
#include <math.h>
#include <boost/math/special_functions/round.hpp>

int main()
{
    long l = -1230695498;

    std::cerr << "boost::math::lround(l) = " << std::setprecision(12) <<
        boost::math::lround(l) << "\n";
    std::cerr << "::lround(l) = " <<std::setprecision(12) <<
        ::lround(l) << "\n";
}

[John Maddock]

Fixed in Git develop. See ​https://github.com/boostorg/math/commit/e6996e118850881ca56b7a9a165fe4f38ab843bc