Ka-Ping Yee has made a module for this, look for this and other amazing stuff at http://www.lfw.org/python/ HTH, __Janko -- Institut fuer Meereskunde phone: 49-431-597 3989 Dept. Theoretical Oceanography fax : 49-431-565876 Duesternbrooker Weg 20 email: jhauser at ifm.uni-kiel.de 24105 Kiel, Germany