Procedure from library linalg.lib (see linalg_lib).
Usage:
minipoly(M); matrix M
Assume:
eigenvalues of M in basefield
Return:
list l; minimal polynomial of M
ideal l[1];
number l[1][i]; i-th root of minimal polynomial of M
intvec l[2];
int l[2][i]; multiplicity of i-th root of minimal polynomial of M