1Function: matindexrank
2Section: linear_algebra
3C-Name: indexrank
4Prototype: G
5Description:
6  (gen):vecvecsmall  indexrank($1)
7Help: matindexrank(M): gives two extraction vectors (rows and columns) for
8 the matrix M such that the extracted matrix is square of maximal rank.
9Doc: $M$ being a matrix of rank $r$, returns a vector with two
10 \typ{VECSMALL} components $y$ and $z$ of length $r$ giving a list of rows
11 and columns respectively (starting from 1) such that the extracted matrix
12 obtained from these two vectors using $\tet{vecextract}(M,y,z)$ is
13 invertible. The vectors $y$ and $z$ are sorted in increasing order.
14