Re: [julia-users] Re: Why A * zeros(..) is faster than A * ones(..)?

[Tim Holy]

I get this:

julia> @time for i = 1:10 A*R end
elapsed time: 7.428557846 seconds (320001120 bytes allocated, 1.43% gc time)

julia> @time for i = 1:10 A*Z end
elapsed time: 7.233144631 seconds (320001120 bytes allocated, 1.46% gc time)

No difference.

Are you using a different BLAS than OpenBLAS?

--Tim

On Thursday, July 17, 2014 07:16:46 AM Andrei Zh wrote:
> Only 2 times faster. But for A = rand(2000, 1000); R = rand(1000, 2000) and 
> Z = zeros() we have:
> 
>  julia> @time for i=1:10 A * R end 
>  elapsed time: 32.497353017 seconds (320001120 bytes allocated, 0.43% gc 
> time)
> 
>  julia> @time for i=1:10 A * Z end 
>  elapsed time: 0.209265586 seconds (320001120 bytes allocated, 70.28% gc 
> time)
> 
> 155 times faster!