Hello,
gnuplot is sent a coma as decimal separator. This does not happen if I change default locale to en_US, (and test1 runs like a charm).
Thanks for the report. Qt is probably changing the locale automatically based on environment variables. A similar problem occured with GraphicsMagick and java.
I solved this for the GUI by calling
setlocale(LC_ALL, "en_US.UTF-8");
right before octave_main. Probably we should file in a bug report for Octave for that. Since Octave only works with this this locale, it should take care to set it properly.
Jacob