SymPy
Why SymPy
SymPy is…
Free: Licensed under BSD, SymPy is free both as in speech and as in beer.
Python-based: SymPy is written entirely in Python and uses Python for its language.
Lightweight:
SymPy only depends on mpmath, a pure Python library for arbitrary
floating point arithmetic, making it easy to use.
A library: Beyond use as an interactive tool, SymPy can be embedded in other applications and extended with custom functions.
See SymPy's features
Projects using SymPy
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Read more at sympy.org