off topic: How could I convert minutes in hour-decimals in a column such as 00:01 00:04 00:07 00:11 00:12 00:13 00:13 00:18 00:19 00:21 00:23 00:32 00:32 .... and more so that e.g. 00:30 becomes 00.50 h either by a unix terminal command or by gnuplot or pyxplot? Wolfgang