GNU Emacs Lisp Reference Manual

3.9: Standard Mathematical Functions

These mathematical functions are available if floating point is supported. They allow integers as well as floating point numbers as arguments.

Function: sin arg

Function: cos arg

Function: tan arg

These are the ordinary trigonometric functions, with argument measured in radians.

Function: asin arg

The value of (asin arg) is a number between -pi/2 and pi/2 (inclusive) whose sine is arg; if, however, arg is out of range (outside [-1, 1]), then the result is a NaN.

Function: acos arg

The value of (acos arg) is a number between 0 and pi (inclusive) whose cosine is arg; if, however, arg is out of range (outside [-1, 1]), then the result is a NaN.

Function: atan arg

The value of (atan arg) is a number between -pi/2 and pi/2 (exclusive) whose tangent is arg.

Function: exp arg

This is the exponential function; it returns e to the power arg. e is a fundamental mathematical constant also called the base of natural logarithms.

Function: log arg &optional base

This function returns the logarithm of arg, with base base. If you don't specify base, the base e is used. If arg is negative, the result is a NaN.

Function: log10 arg

This function returns the logarithm of arg, with base 10. If arg is negative, the result is a NaN. (log10 x) == (log x 10), at least approximately.

Function: expt x y

This function returns x raised to power y. If both arguments are integers and y is positive, the result is an integer; in this case, it is truncated to fit the range of possible integer values.

Function: sqrt arg

This returns the square root of arg. If arg is negative, the value is a NaN.