diff options
Diffstat (limited to 'doc/lispref/numbers.texi')
| -rw-r--r-- | doc/lispref/numbers.texi | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/doc/lispref/numbers.texi b/doc/lispref/numbers.texi index cffc634169f..fbdd83fa86e 100644 --- a/doc/lispref/numbers.texi +++ b/doc/lispref/numbers.texi @@ -313,14 +313,18 @@ and returns the result. @var{x1} and @var{x2} must be floating point. @defun logb x This function returns the binary exponent of @var{x}. More -precisely, the value is the logarithm base 2 of @math{|x|}, rounded -down to an integer. +precisely, if @var{x} is finite and nonzero, the value is the +logarithm base 2 of @math{|x|}, rounded down to an integer. +If @var{x} is zero, infinite, or a NaN, the value is minus infinity, +plus infinity, or a NaN respectively. @example (logb 10) @result{} 3 (logb 10.0e20) @result{} 69 +(logb 0) + @result{} -1.0e+INF @end example @end defun |