Sicyon Calculator is a powerful tool for scientists and engineers.
The program opens much like many other scientific calculators. There's a numeric keypad, the basic operators, then buttons of functions which you can use as required.
A quick glance at the toolbar reveals that this is just the start. You can fit curves, find minimums/ maximums/ integrals, derivatives and roots, generate graphs, convert units and more.
There are also tools to use matrices and matrix calculations, explore various physical or chemical constants, along with a simple spreadsheet-like table for entering data.
If this isn't enough, you can create and access VBScript or JScript functions from the program, even run program code on demand from the main window.
The interface isn't straightforward and the "help" doesn't always help, but there's no doubting Sicyon Calculator's scientific abilities. Worth a look to get a feel for what it can do.