[eigen] [Sparse][LU] scale factors

[<bernard.hugueney@xxxxxxxxxx>]

Hi,
I'm using SuperLU and UmfPack backends for Sparse matrix LU 
decompositions.
Those backends expose the P and Q permutations, but not the scaling 
factors
(I believe that SuperLU backend gets them but does not give access[0], 
while UmfPack backend does not read the
scaling factors [1], for UmfPack, one would also need acces to the 
do_recip flag).

Are there some strong reasons not to provide those access ?

Best regards,

Bernard

PS: Is there a "nice" way to convert the permutations vectors to sparse 
matrices such that P* and *Q do the permutation ?
I'm well aware that this would not be the proper way to perform those 
permutations, but I need thoses sparse matrices anyway
, and my current code reading the values in the vectors and setting the 
1. by hand in the sparse matrix feels ugly.


PS2: I saw that Scipy patched SuperLU [2], and while I'm against 
embedding libraries, those patches seem serious ☹

[0] 
https://bitbucket.org/eigen/eigen/src/tip/unsupported/Eigen/src/SparseExtra/SuperLUSupport.h#cl-370
[1] 
https://bitbucket.org/eigen/eigen/src/10990f843213/unsupported/Eigen/src/SparseExtra/UmfPackSupport.h#cl-306
[2] 
http://projects.scipy.org/scipy/log/trunk/scipy/sparse/linalg/dsolve/SuperLU/SRC?rev=6355