Mathematica Note CalculationCenter is a Mathematica-based product intended for practical engineers who need a convenient, relatively inexpensive product that does calculations, makes plots, makes their life easy, etc. One of its nicest features is that it uses Mathematica's symbolic computing capability to do dimensional analysis in a very sophisticated way. You can enter all quantities in a formula with their full units, and if they don't balance out in the end, you know something is wrong. CalculationCenter can also automatically combine and convert different unit systems, so if you want to calculate the weight of a gas inside a volume you know in inches, with a pressure you know in millitorr, and an atomic weight you know in grams, you can do this without needing any explicit conversion factors: It automatically looks at the units, converts them to a compatible set, and does the math. This is pretty spiffy.