Igor has a large number of built-in mathematical functions which can be roughly divided into four groups:
Elementary Functions include functions that are usually provided by most CPUs e.g., trigonometric functions.
Special Functions are distinguished by the fact that they are usually a bit more difficult to compute but they appear often enough in applications to justify the convenience of built-in accessibility.
Utility Functions provide easy and quick manipulation of data.
Statistical Functions include probability distributions (PDFs), cumulative distribution functions (CDFs) and their inverses. These functions are covered here.