My company, *Greer Software Products*, produces mathematical software tools for the Macintosh platform, useful to students and professionals alike. My main product, MatrixCalc, does the work of commercial software packages for a fraction of the cost.

MatrixCalc is an easy-to-run interactive tool for making calculations in linear algebra, solving linear and nonlinear least squares problems, performing eigen analysis, singular value decomposition, and spectral analysis. Spectral analysis algorithms include the FFT and Maximum Entropy. Data may be generated, imported, smoothed, and plotted. Elements of a matrix may be matrices and/or matrix expressions.

The basic element in MatrixCalc is a matrix and the driver behind MatrixCalc is a parser which processes and evaluates matrix expressions. Dynamic allocation of memory enables one to work with large matrix arrays. Since a real number is defined as a matrix with one row and one column MatrixCalc easily handles real number calculations.

Text windows may be opened and used as scratch pads to evaluate expressions and a number of these windows may be open at one time. Selecting a particular window by clicking on it makes that window active or "hot". Variables are global. Therefore, a variable created in one window may be used in another.

Macro files (containing executable statements) may be created with the text editor (or any other text editor), saved, and executed with the interpreter. The interpreter allows a simple programming language consisting of: for, goto, if-then, begin, end, and execute commands. Macro files may call other macro files with the execute command.

Matrix files containing real numbers may be imported and exported to other applications. Matrices, macro files, and plots may be printed and/or saved for future used.

MatrixCalc can be used to study some of the properties of matrices and there are many examples in the Demo folder.

MatrixCalc was compiled with the Symantec Think Pascal 4.0 compiler on a Quadra 630. Two versions were created - MatrixCalc68000, and MatrixCalc68040. The MatrixCalc68000 version will work on a Mac Plus or higher and the MatrixCalc68040 on a Macintosh with a math coprocessor. Computations are faster using a coprocessor.

- Plot of Periodic Functions
- NonLinear Model
- Linear Model
- Fast Fourier Transform (FFT)
- Maximum Entropy vs FFT
- Smoothing By Polynomial and Moving Average
- Matrix Partitioning
- Eigenvalues/vectors of a Real Symmetric Matrix
- Singular Value Decomposition
- Binary Operations
- Function Operations

- Download version for Mac without Math Coprocesser.
- Download version for Mac with Math Coprocesser.
The price of MatrixCalc is $40. Upon receipt of payment, I will send you the full application with help files.

MatrixCalc is copywritten by Bill Murray, Greer Software Products.

You can email me at sisu31@aol.com

My snail mail address is:

Bill Murray

8521 Chapel Drive

Annandale, Virginia 22003

(703) 978-3327