Chalk is a calculator application for your Mac. It looks like a simple tool, but in fact it hides great abilities. It supports complexes, quaternions, matrices, and lists. Chalks supports absolute and relative uncertainty, meaning that you can compute a sequence of operations with uncertainty and get the uncertainty of the result. It can decompose numbers and test primality. If the answer is probabilistic, it reports that fact. It can handle different bit representations and interpret an unsigned integer as a float, roll, shift, and so on. You can use it cleverly to display unambiguous graphs, where the uncertainty is reported, and no data disappear because of subsampling. Chalk is also able to display a set of constraints (equalities, inequalities) to determine 2D areas of (x, y) predicates.
