Free and opensource math graphing software
ZeGrapher is a plotting program for functions, sequences, parametric equations, and tabular data. It has been designed to be as easy to use as possible. ZeGrapher supports importing and exporting of tabular data from and to CSV files and polynomial (regression) fits, plotting of tangents (the point can be selected interactively). Calculation and plotting of derivatives and integrals is also possible. Plots can be exported in various image formats and as PDF files.