On 1/23/07, Cromwell Enage
--- Sami wrote:
On 1/22/07, Sami wrote:
Hi Tony,
Thx for your reply first of all.
On 1/22/07, Gottlob Frege wrote:
On 1/22/07, Sami wrote:
Hi All,
if (Pow == 0) return 1; // to do argue about
0'. if (Pow == 1) return r; return pow
(r) * r; }
Now, why do you want it - I doubt that it will buy you anything in terms of performance. The issue is not particularly about performance, it is about being able to do this at compile time; other than, well,
resolution to the problem is quite nice, though
the value of '0 to the trying out MPL. Your that's not what I am asking.
My question is about MPL, not "how to do this with C++"...
There should be a way of doing this using MPL with a single line of code. Or, even compute integer power of integers and get a compile time result. This is useful for many metaprograms and again, not a performance concern.
Any ideas?
One more note. In my original post, I mentioned this constant sequence wrapper. If there were such a thing (is there?) then one could evaluate integer power of an integer at compile time. For instance:
const unsigned SIZE = 3; const unsigned EIGHT = fold ( constant_sequence< int_<2>, SIZE >, int_<1>, times< _ , _ > :: type :: value ;
This is only a thought. Maybe there is a better way of computing powers, without using fold or that constant_sequence thingy..
As for the real powers, maybe there is a Boost.Fusion algorithm that can do it..
Actually, there are two MPL algorithms in the Boost Vault < http://boost-consulting.com/vault/ >. Look inside the Template Metaprogramming folder for mpl_math.zip; the algorithms are integral_power and power, IIRC.
Cromwell D. Enage
wouv! This library blew my head off. I was only asking for a silly single line statement, look what you have done in there! I am so surprised that this library is buried down in the vault and didn't make it to Boost collection yet.. thanks Cromwell. sami