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   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.
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