Manipulate algebra. Integrals found & explained. Define own functions and constants. Find Standard Deviation etc. Plot functions. Solve Triangles. Least Squares fits, inc. nonlinear, Simultaneous Linear/Nonlinear Equations. Polynomial Roots. More.
Pros: This program too has a unusual approach to the interface. This is really a single line entry window to leave the screen free for other use. Additionally, this window can be partially transparent when inactive, so you can read documents open underneath it. It is a collection of mathematical tools in one program, for use by scientists, engineers and students. The main window is a calculator that accepts mathematical expressions as plain text and evaluates them to 38 digit precision. The symbolic algebra module helps simplify expressions, differentiate them, and integrate a range of expressions and so on. Finding Taylor series, factorizing polynomials, division of polynomials etc are things that can be done easily.
Statistical analyzes like standard deviation, finding mean/median/skewness, of a dataset is easily done with the functions available. These allow linear regression or polynomial fitting are also features of this set of functions. Analyzing a set of measurements and approximating complex functions with simpler curve fitting is also possible with the calculator. Multivariate analysis is also possible. Solving non linear equations is assisted by root finding, solving of triangles etc.
The calculator also facilitates plotting of arbitrary functions when starting and end conditions are specified, up to 8 such plots can be combined. Recording of history and storage of curves as images for future reference provide support to all of the above.
Cons: Effective use of the calculator would need training in the specific areas of functionality. Not all functionality thus can be used by any one group of users who may not have training in other areas. But then these are specialized functions anyway.
Overall: This is a full featured application for useful calculations required by specialized groups of people. This is at the 4 star level quite easily.