 IN MATH: 1. n. a way of testing a graphed function to determine if it is 1-to-1, uses each y-value at most once, has the possiblility of having an inverse function. EX. The graph of y=x² fails the horizontal line test because one or more horizontal lines pass through the curve simultaneously. The line through (-2,4) and (2,4), for example.

 See: Graphing with Manipulatives & Exploring Functions - ANIMATIONS!!!!, translations, reflection! - Graphing w/Manipulative, Exploring Functions TOOLS   A Graph is A Portrait - an essay on the concepts of graph GRAPHITI - introductory coordinate geometry, point generation, distance, functions Point-Plotting Animation - see step-by-step how to create a graph Slope in Sound & Picture - Algebra Notes What's a Function? - Index on topics like "How Functions Are Composed or Created", "Polynomial & Rational Functions" "Finally ... Functions" -- an introduction to functions as a direct consequence of operations Functions & Operations -- a page that computes & illustrate how functions work - Function and Relation Library - Many functions w/their features & graphs Graphing Vocabulary Function Vocabulary

IN ENGLISH: 1. as defined above.

APPLICATION: See list 300. 