Re: ilu function

[Marco Caliari]

Dear Giovanni,

thank you very much for considering the inclusion of your 
implementation of ILU function in core Octave.
Of course your actual implementation (maybe rewritten in Octave style) is 
fine for small matrices, and in fact you are considering to "translate" to 
C language to improve the performance.
However, since the code will be used for sparse matrices, it is not just a 
translation needed, but a complete rewriting using the CCS format.
Some months ago, I also tried to write the ilu(0) factorization and I 
ended up with some files here enclosed. Basically, luincfull.m is your 
nofill.m and luincsparse.m is the same done with vectors data, ridx, cidx 
of CCS format. If you run testluincsparse.m, you discover that even in 
Octave language the sparse version is faster.
To conclude, it is a translation into C of luincsparse.m and not of 
luincfull.m that we need. The result would be very similar to subroutine 
ilu0 in chapter 10 in Saad's book, except that we should use the CCS 
format and not the CSR (if you are interested, I translated luincsparse.m 
into Fortran).
At that time, I stopped working on it and contacted Saad, who knows and 
uses Octave

http://www-users.cselabs.umn.edu/classes/Spring-2012/csci8314/matlab/index.html

and he, or some students of him, were quite interested into the project 
(writing ilu for Octave), but since then (April 2012) I got no more 
answer.

Cheers,

Marco

luinc.tar.gz
Description: Binary data