Sympy

When you need exact mathematical results instead of floating-point approximations, this is your tool. It handles symbolic algebra, calculus (derivatives, integrals, limits), equation solving, and symbolic linear algebra. The skill covers everything from basic simplification to physics calculations and code generation via lambdify or LaTeX export. Key practice: always use Rational or S() for exact arithmetic instead of Python floats, and leverage symbol assumptions (positive, real, integer) to get cleaner simplifications. When you need to evaluate expressions thousands of times, convert to NumPy functions with lambdify rather than repeatedly calling subs(). Requires Python 3.9+ and SymPy 1.14+.