Mathcad - engineering calculation solution, is used by engineers and scientists in various disciplines: mechanical, electrical, and civil engineering. Mathcad today includes some of the capabilities of a computer algebra system, oriented towards ease of use and simultaneous documentation of numerical engineering applications. Mathcad is computer software primarily intended for the verification, validation, documentation and re-use of engineering calculations.
MathCAD is an amazingly powerful engineering tool in the right hands. It is almost an essential tool when working with a lot of different units for design purposes. From the outside perspective of a new user it may seem like a simple place to dump x:=3, but it is so much more powerful than that. The ability to perform numerical methods, multi-variable problem solving, parametric design studies, and symbolically solve differential equations brings this program to a whole new level. I use the program mainly as a design tool when working with different units, such as pressure calculations, force calculations, and heat transfer. Perhaps you only know the thermal conductance of a material in English units but need SI? MathCAD will do the conversion for you so you can just keep working. However, my biggest gripe with the program is troubleshooting syntax or logic errors. You will spend an exorbitant amount of time tracking down a naming error or matrix/index problem. The "error tracing" features are not very useful.