Matthias Schabel said: (by the date of Mon, 28 Nov 2011 08:01:31 -0800)
a += dd*exp(i*k*r)/r;
I don't think you missed anything and I think that your second expression should work as expected. I would consider it a flaw in Boost.Units that this does not currently work and a flaw in C++ that getting a (relatively) simple mathematical concept like dimensional analysis to function in a library is as difficult as it is...
I am attaching error log for this single line change. gcc version 4.4.5 (Debian 4.4.5-8) boost 1.42 that's what I currently use. But I can update if required, especially boost version :)
The currently sanctioned approach to function arguments is to use templates to accept any unit of the appropriate dimension, but it does make more sense to allow implicit conversion in the special case of scaled units. The only issue is the danger of roundoff/truncation problems.
if orders of magnitude are greater than used precision (double, for example) a warning could be emitted. But not a critical error, I think. People should write their code to compile without warnings.
And those short names are carefully designed to not have any unit name clashes.
I guess we could have a header corresponding to each SI unit that contains predefined scaled units for each of the SI prefixes. I'll try to get you something to start with later today.
that will be great, thanks :) best regards -- Janek Kozicki http://janek.kozicki.pl/ |