Hello Jean_Marc, Thank you for your suggestions. All of them has been very accurate and useful. --------------------------------------------------------------- o o o Francesc Burrull i Mestres Tel: +34-934016012 o o o Fax: +34-934015981 o o o Matematica Aplicada i Telematica U P C Universitat Politecnica de Catalunya [EMAIL PROTECTED] http://www-mat.upc.es/~fburrull c/ Gran Capita s/n. Campus Nord, Modul C3-320. 08034 Barcelona ---------------------------------------------------------------
