Sven Schreiber wrote: >> In the old file I created a matrix on the fly. I know that Numpy and >> python cannot do that so I found a workaround
numpy can create matrices on the fly, in fact, you are doing that with this code! The only thing it doesn't do is have a lateral that joins matrices the way matlab does -- you need to use vstack and the like. >> First I create the empty matrix To get better performance, you could create the entire empty matrix, not just one row -- this is the same as MATLAB -- if you know how big your matrix is going to be, it's better to create it first with "zeros". In numpy you can use either zeros or empty - just make sure that if you use empty, you fill the whole thing later, or you'll get garbage. Your code: lev2=empty((1,h)) # you've just created and empty single row . . . lev2=vstack((lev2,clev)) #now you are creating a whole new array, with one more row than before. The alternative: lev2=empty((nstep+1,h)) 3 create the whole empty array ir=1 for j in arange(1,nstep+2): a2=gr[arange(ir-1,ir+nstep)] clev=diag(dot(a2,dot(disper,a2.transpose()))) lev2[j,:] = clev # fill in the row you've just calculated ir=ir+nstep+1 print lev2 I may have got some of the indexing wrong, but I hope you get the idea. By the way, if you sent a complete, runnable sample, we can test out suggestions, and you'll get better answers. -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception [EMAIL PROTECTED] _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
