Mather is a powerful, simple-to-use, no BS expression-based computation engine.
In addition to basic calculator arithmetic, it supports all of the following.
Powered by Math.js.

* Variables
* User-defined functions
* Easily-accessible math constants, e.g. 'pi'
* Complex math expression evaluation
* Trigonometric functions
* Unit conversions (and more general unit arithmetic)
* Complex numbers
* Matrices
* and more