[GRASS-dev] Re: [GRASS-user] Compiling addons from svn repository

[Moritz Lennert]

Gianluca,

On 04/08/08 14:52, gianluca massei wrote:
> Thanks Moritz , great tip!
> I'm working in a module that implemented ELECTRE algorithm.
> 
> I've just finisced a module named /r.roughset/ for knowledg discovery 
> with rough set based on rough set library. You can download the source 
> code from grass wiki 
> (http://grass.osgeo.org/wiki/GRASS_AddOns#r.roughset) and I'm happy if 
> sameone caould try it and report me tips or bugs.

Together with a colleague we are trying out your r.mcda.* multicriteria 
analysis [1] suite to work.

At this stage, we cannot comment on any results, yet, but just on the 
fact that it seems that the region and resolution settings have to be 
very restrictive (small region, coarse resolution) for the modules to 
work, otherwise we get out of memory errors (tested in with *.electre 
and *.regime).

This is due to the fact that you use a matrix which is 
(nrows*ncols)*(nrows*ncols), e.g. in lines 142 and 143 of 
r.mcda.electre/main.c

concordance_mat=G_alloc_matrix((nrows*ncols),(nrows*ncols));
discordance_mat=G_alloc_matrix((nrows*ncols),(nrows*ncols));

This means that on my computer the limit is a region of around 13000 
cells, i.e. ~ 115 rows * 115 columns which really is not a lot.

Do you think there might be a different way of coding this to avoid 
using up so much memory ?

Moritz

[1] svn co https://svn.osgeo.org/grass/grass-addons/raster/mcda/