Minsky
System dynamics program with additional features for economics
...Minsky's unique feature is the "Godley Table", which uses double entry bookkeeping to generate stock-flow consistent models of financial flows.
Minsky is good for demonstrating mathematics too, with the most "math-like" interface in system dynamics.
Sign up to Minsky's Patreon page (for as little as $1 a month) at https://www.patreon.com/Ravelation/. This creates a user community, which SourceForge doesn't facilitate.