The classic "Handbook of Mathematical Functions" edited by Milton Abramowitz and Irene Stegun is now on IOS. This edition of the Handbook contains more than 4000 equations and 170 graphs/illustrations. Interactive calculators have replaced bulky tables.
The Handbook contains a huge amount of information for students, scientists and engineers who need quick access to a wide variety of mathematical formulas. Buy it once, use it forever.
Subjects include common transcendental functions and formulas, orthogonal polynomials, integrals, series, coefficients, sums, transforms, recurrences and relations. The entire text is searchable.