Calculus Made Easy is a book on
infinitesimal calculus originally published in 1910 by
Silvanus P. Thompson, considered a classic and elegant introduction to the subject[citation needed]. The original text continues to be available as of 2008 from
Macmillan and Co., but a 1998 update by
Martin Gardner is available from
St. Martin's Press which provides an introduction; three preliminary chapters explaining
functions,
limits, and
derivatives; an appendix of
recreational calculus problems; and notes for modern readers. Gardner changes "fifth form boys" to the more American sounding (and gender neutral) "high school students," updates many now obsolescent mathematical notations or terms, and uses American decimal dollars and cents in currency examples.
Calculus Made Easy ignores the use of
limits with its
epsilon-delta definition, replacing it with a method of approximating (to arbitrary precision) directly to the correct answer in the
infinitesimal spirit of
Leibniz, now formally justified in modern
nonstandard analysis and smooth infinitesimal analysis.
The original text is now in the
public domain under
US copyright law (although Macmillan's copyright under UK law is reproduced in the 2008 edition from St. Martin's Press). It can be freely accessed on
Project Gutenberg.