SM

supermongo is a graphing and plotting package that can be found ​here.

It is ​not free. In particular, the Cost section says:

SM is available for $300 U.S., $375 Canadian to university departments, or small colleges. A university-wide site license is $1500 U.S., $1900 Canadian. Prices for commercial or government agencies are $500 U.S. for a department, $2500 U.S. for an entire site.