Re: [Boost-users] Xcode - Slow

Subject: Re: [Boost-users] Xcode - Slow
From: Christopher Jefferson (chris_at_[hidden])
Date: 2010-06-30 12:09:58

On 30 Jun 2010, at 16:55, Raphaël Amiot wrote:

> Hello there.
> 
> I am implementing matrix multiplication and am trying to have my stuff run as fast as possible.
> But then I noticed something strange. 
> Using Xcode,
> 
> resultmatrix = prod(matrix1,matrix2);
> 
> is 10 to 16 times slower (with 100x100 matrixes) than simply doing something like that: 
> 
> 
> for(...)
> 	for(...)
> 		for(..)
> 			multiply_things();
> 
> And 20 to 40 times slower than a simple threaded approach.
> 
> 
> Using visual studio, it's 2 times faster than naive multiplication.
> 
> 
> This is on a release build, with 
> #define BOOST_UBLAS_NDEBUG 1
> #define NDEBUG 1
> 
> So what gives?_______________________________________________

Could you provide a small complete program which shows your problem?

Chris