ufs_radicalbase, ufs_corank - compute the radical of a quadratic form

Calling sequence:

ufs_radicalbase(M)

ufs_corank(M)

Parameters:

M - a symmetric matrix

Synopsis:

ufs_radicalbase calculates a basis of the radical of the quadratic form associated to the matrix M.

ufs_corank calculates just the length of such a base.

The argument must be a symmetric matrix, otherwise an error occurs.

Example:

> A:=matrix([[2,-2,0,0,1],[-2,2,0,0,-1],[0,0,2,2,0],[0,0,2,2,0],[1,-1,0,0,2]]);

> ufs_radicalbase(A);

> ufs_corank(A);