Derive is not available for Mac but there are plenty of alternatives that runs on macOS with similar functionality. The best Mac alternative is GNU Octave, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Derive and many of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Derive are MATLAB (Paid), Mathematica (Paid), Scilab (Free, Open Source) and SageMath (Free, Open Source).
WolfCalc is a light minimal front end to the powerful Wolfram|Alpha™ Computational Knowledge Engine™, which is one of the most powerful calculators in the world and can be used to solve a large variety of problems.
StochSD (Stochastic System Dynamics) is a System Dynamics simulation software with focus on stochastics. It is a form of Continuous System Simulation (CSS) that in addition to model and simulate continuous flows between compartments, can handle transitions of discrete entities.