Re: C++ optimization help with the creation of temporaries

[edA-qa mort-ora-y]

Ulrich Eckhardt wrote:
> Two things here: I personally prefer implementing binary operators where
> there is no main or principal object involved as unbound function instead
> of member function. That's a matter of taste though.

Well, I'll try that and see if it helps the optimizer.


> >         for( unsigned i=0; i < dim; i++ )
> Ideomatic (but I don't think it's faster here) would be to use 'i!=dim' and
> '++i'. Should be in any beginners introduction to iterators and for loops.

The beginner's book was probably different 15 years ago when I learned 
the loop. ;)

> Finally, one things you could try is to apply (partial) specialisation for
> this, unrolling the loop for some cases. Maybe the boost metaprogramming
> library might help you in that task, but I'm no expert in that field.

I had tried many variations on that already, and strangely everything I 
did by hand (unrolling, specialization, etc.) ended up making it slower.

>  A last thing I noticed is that sometimes float is faster than double. This
> strongly depends on the processor though, so never hard-wire either choice
> into your program.

The "rtype" is either a double or long double in my program, and 
although I know the float is faster in our program (from testing), it 
doesn't have the precision we need (we're borderline needing long double).

--
edA-qa mort-ora-y
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