SMath Studio is a freeware, closed source, mathematical
notebook program similar to Mathcad, written in C#.

Among its capabilities are:

 - Solving differential equations
 - Graphing functions in two or three dimensions
 - Symbolic calculations including solving systems of equations
 - Matrix operations including determinants
 - Finding roots of polynomials and functions
 - Symbolic and numeric differentiation of functions
 - Numeric integration
 - Simple multiline looped programs
 - User defined functions