Function `lsolve()'

Dear all, we need to use the function `lsolve()' that appears on page 5 of the tutorial for GiNaC 1.0.10, but not in the Concept Index. We couldn't find it elsewhere, not even in the specifications for the class matrix. We would like to know its specifications, if possible. In particular, we have linear systems whose associated matrix may have some linear dependencies. Thank you very much in advance Alessandro Zaccagnini and Tatiana Zolo