[boost] speed of light from universal_constants Boost.Units

Subject: [boost] speed of light from universal_constants Boost.Units
From: Roger Martin (roger_at_[hidden])
Date: 2014-03-10 13:12:58

Hi,

I've tried and tried and just not understanding or can't muddle my way 
through the boost units(looks powerful though).  For a start, just 
trying to get at the speed of light in
boost/units/systems/si/codata/universal_constants.hpp

boost::units::si::constants::codata::c
boost::units<boost::units::si>::constants::codata::c.value()
and massive errors; especially if I try to multiplying with something.

I use boost::math::constants::pi<double>() from
#include "boost/math/constants/constants.hpp"

But the universals allude me; and example? where is my brain stuck?