The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
An inverse function is one which reverses the action of a previous function. That is, it takes the value from the previous function and returns it to its previous value for all values of that function. Many inverse functions are familiar --for example, if the function in question was y = 2x, it would be clear that z = y/2 would return z = x. Some functions are their own inverse--for example, y = 1/x results in z = 1/y as an inverse. Some functions lack inverses.
Other inverse functions present special problems. For example, cyclic functions like the sine and cosine function require a specified interval, since the sine and cosine will range between zero and one in exactly the same way from zero to infinity in both directions, positive and negative. In this case, a two pi interval is required to secure the desired inverse value. For other functions, there will only be two or three ranges that can be selected out of all numbers. For example, if one is taking the square root of a number, one must specify whether one wants the positive or negative value of the square root. This specification is what is necessary to make the inverse function a function, mapping on a one-to-one basis, rather than a mere number relation, which might have two or more valid results. In practical situations, it is usually clear which values apply.