GNU Emacs Lisp Reference Manual
3.9 Standard Mathematical Functions
These mathematical functions 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.