EXTREMA is an interactive program with publication quality graphics and mathematical analysis capabilities. Over 200 numeric and character functions are provided, as well as over 30 operators, providing all of the operations of simple calculus, along with powerful curve fitting, filtering and smoothing techniques, and employing a dynamic array management scheme allowing arrays limited in size only by system resources. Algebraic expressions of arbitrary complexity are evaluated using a lexical scanner approach. Line graphs, histograms, as well as contour and density plots are available. Extrema is a powerful visualization and data analysis tool that enables researchers to quickly distill their large, complex data sets into meaningful information. Its flexibility, sophistication, and power allow you to easily develop your own commands and create highly customized graphs. The graphical user interface is backed by a command language with a simple to use and easy to learn syntax, incorporating basic elements of a structured programming language including conditional branching, looping and subroutine calling constructs.