Michael
Posts:
4
Registered:
3/26/12


Re: Speeding up calculation of matrix
Posted:
Mar 27, 2012 9:43 AM


"Roger Stafford" wrote in message <jkql7d$5r1$1@newscl01ah.mathworks.com>... > "Roger Stafford" wrote in message <jkqh5t$ka3$1@newscl01ah.mathworks.com>... > > [py,px] = ndgrid(0:fit_y,0:fit_x); > > M = bsxfun(@power,x,reshape(px,1,[]))+bsxfun(@power,y,reshape(py,1,[])); >           > As a third alternative you could try this to minimize the total number of power operations (70 vs 240): > > n = size(x,1); > M = reshape(bsxfun(@plus,bsxfun(@power,y,0:fit_y), ... > reshape(bsxfun(@power,x,0:fit_x),n,1,[])) ,n,[]); > > Roger Stafford
Thanks Roger  I am getting about a 30% reduction in run time using this method (after replacing the first function call to @times instead of @plus). Exactly the kind of solution I was looking for. The solution using ndgrid ran a bit slower  the ndgrid call took a while to compute.
Thanks again, Michael

