[Help-gsl] Compute null space of a matrix using SVD

[Christophe Dehais]

I'm trying to compute the null space of a matrix A with M < N, using
the residual singular vectors of the SVD decomposition of A.
However, as the SVD code doesn't allow M < N, I have to work on A tanspose.
I could use the fact that if A' = U.S.V' then A = V.S.U' and return
the last vectors of U, but U is actually truncated because we compute
a thin SVD,
so some (or all in case M is full rank) vectors of M's null space are lost.

I'm guessing that either the SVD code should support the case M < N or
there should be an option to compute the full SVD decomposition.

Or is there another alternative I could use ?

thanks,
Christophe