On 7/1/2011 1:05 PM, Cromwell Enage wrote:
--- On Fri, 7/1/11, Kenny Riddile wrote:
This isn't directly Boost-related, but this is still probably the best place to ask this question. Just for fun, I was trying to write a compile-time approximation of cosine using the following Maclaurin series:
cos( x ) ~= 1 - ( x^2 / 2! ) + ( x^4 / 4! ) - ( x^6 / 6! ) + ...
I ended up at a point where I needed to assign a const floating point value to the result of an integer division, kind of like this:
static const float value = integerA / integerB;
My problem is of course that you can't cast to non integral/enum types in a constant expression, which means that I end up with the truncated result of integer division. Suggestions?
If your code really needs to perform compile-time floating-point math, then I have two suggestions:
1. Use the recently accepted Boost.Ratio library (which should become part of the next release).
2. Try out the MPL.Math sublibrary (not yet accepted into Boost, currently located at<https://github.com/boost-vault/Template-Metaprogramming/blob/master/mpl_math.zip>) and browse the existing source code. Sorry, no real documentation yet.
HTH, Cromwell D. Enage
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I was just trying it for fun. I already had a preprocessor macro solution, but wanted to see how feasible a pure TMP solution would be. This is fairly accurate though: http://pastebin.com/jz69vxYn