The organization of IMSL MATH LIBRARY Special Functions closely parallels that of the National Bureau of Standards’ Handbook of Mathematical Functions, edited by Abramowitz and Stegun (1964). Corresponding to the NBS Handbook, functions are arranged into separate chapters, such as elementary functions, trigonometric and hyperbolic functions, exponential integrals, gamma function and related functions, and Bessel functions. To locate the right routine for a given problem, you may use either the table of contents located in each chapter introduction, or one of the indexes at the end of this manual.