EXTREMA is a high level, interactive programming environment with user friendly graphics and sophisticated 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 and pie charts, as well as contour, density and surface plots are available. The user interface is 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.