Don't forget Gnuplot! www.gnuplot.info . Fast, easy to learn, and flexible. Will do limited curvefitting, but it's not an analysis tool.
I use it for quick and for final plots. Any intermediate analysis gets done in Octave (which has abandoned the gset commands for MATLAB compatibility).
I use it for quick and for final plots. Any intermediate analysis gets done in Octave (which has abandoned the gset commands for MATLAB compatibility).