[boost] [Math] acosh implementation

From: Szymon Modzelewski (angelofpromise_at_[hidden])
Date: 2008-08-06 16:38:00

http://svn.boost.org/svn/boost/trunk/boost/math/special_functions/acosh.hpp

goes like this:

static T const    taylor_2_bound = sqrt(tools::epsilon<T>());

// this is way smaller than 1
static T const    taylor_n_bound = sqrt(taylor_2_bound);

static T const    upper_taylor_2_bound = one/taylor_2_bound;

if(x < one) // right
{
    return policies::raise_domain_error<T>(
       "boost::math::acosh<%1%>(%1%)",
       "acosh requires x >= 1, but got x = %1%.", x, pol);
}
else if    (x >= taylor_n_bound) // what?
{
...
}
else
{
  // so when do we actually get here?
  ...
}