On 11/8/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > I told my friend about how nice J was. Am I wrong? > > He said, how fast can you multiply a 1000x1000 matrix times > a 1x1000 vector to get a 1x1000 resultant vector. > > his MatLab code ran in about .6 seconds. > > His code follows.. > > matrix = randn(312,256); > vector = randn(256,1); > > tic > for i = 1:1000 > output = matrix*vector; > end > toc
I do not see a 1000x1000 matrix here, nor a 1x1000 'vector' -- I think he's making up the data as he goes along. That said, I think the J version of this would be: matrix=: 256+?1000 1000$1+312-256 vector=: ?1000 1$1+256 result=: matrix +/ .* vector -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
