This is a Terminal UI app written in Rust.
It is a Reverse Polish Notation (RPN) Calculator that allows for many different expressions including basic operations (+,-,/,*), exponents, logs, angles, factorials and more.
RPN calculators differ from the traditional calculators by the fact that you enter in all of the numbers first, and then any operator you enter is applied to the last 2 numbers. For example 5 + 4 becomes 5 4 +. This leads to some very simplified expressions such as (3 + 4) × (5 + 6) becomes 3 4 + 5 6 + ×. This removes the need for brackets or the order of operations, as each step is performed individually, saving on keystrokes and time, and lowering the amount of errors made.
There are also extra features to swap numbers, duplicate numbers, clear and delete.
There is working undo and redo stacks, so you can go back to previous states if you make a mistake.