AlphaPlot is an open-source computer program for interactive scientific graphing and data analysis. It can generate different types of 2D and 3D plots (such as line, scatter, bar, pie, and surface plots) from data that is either imported from ASCII files, entered by hand, or using formulas.
PSPP
GNU PSPP is a program for statistical analysis of sampled data.
Octave
Scientific Programming Language
LabPlot
LabPlot is a free software and cross-platform computer program for interactive scientific graphing and data analysis, written for the KDE desktop.
Óreiða
XaoS (pronounced chaos) lets you dive into fractals in one fluid, continuous motion.