fend is an {Arbitrary-precision unit-aware calculator.} It features: Arbitrary-precision arithmetic using rational numbers, Full support for complex numbers, D&D-style dice rolls, Variables, Binary, octal, hexadecimal and all other bases between 2 and 36, The ability to keep track of units, with support for SI, US and UK customary and many historical units, Emacs-style CLI shortcuts, Trigonometric functions, and Lambda calculus

WWW: https://printfn.github.io/fend
