[R-sig-dyn-mod] Vectorizing

[Stephen Ellner]

Unfortunately, the only method I know for mastering vectorizing is practice, practice, practice, 
after looking at the pointers that Thomas suggested. The PDE application that I
described worked in R because it was possible to compute once-and-for-all matrices such that
all the calculations needed to compute approximate spatial derivatives were done with 
two matrix-vector multiplications (one each for first and second derivatives). I have 
very little experience with ABMs, so I don't know how frequently there are tricks like 
that which make loops go away. Maybe others on this list can provide some examples? 

Steve Ellner

>Date: Sun, 6 Nov 2011 07:34:24 -0600
>From: E Michael Foster <emfoster at uab.edu>
>To: Special Interest Group for Dynamic Simulation Models in R
>        <r-sig-dynamic-models at r-project.org>
>
>Thanks so much for taking the time to respond.  
>
>This is kind of what I feared and I know about the benefits of vectorizing calculations.  
>My difficulty is that the idea of loops is so drilled into my brain 
>
>Know of a good resource for mastering vectorizing calculations?  
>Googling, I certainly can see plenty of instances where folks are asking for help on technical problems--
>
>E. Michael Foster
>Professor, Department of Health Care Organization and Policy 
>School of Public Health 
>The University of Alabama at Birmingham 

Stephen P. Ellner (spe2 at cornell.edu) 
Department of Ecology and Evolutionary Biology
Corson Hall, Cornell University, Ithaca NY 14853-2701
Phone (607) 254-4221    FAX (607) 255-8088
* This is my work email. I try not to read it at other times *