diff options
Diffstat (limited to 'manual/arith.texi')
| -rw-r--r-- | manual/arith.texi | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/manual/arith.texi b/manual/arith.texi index 3a6bb434de..563d9859af 100644 --- a/manual/arith.texi +++ b/manual/arith.texi @@ -2,17 +2,23 @@ @ifclear cdot @ifhtml @set cdot · +@macro mul +· +@end macro @end ifhtml @iftex -@set cdot @cdot +@set cdot · +@macro mul +@cdot +@end macro @end iftex @ifclear cdot @set cdot x -@end ifclear @macro mul -@value{cdot} +x @end macro @end ifclear +@end ifclear @node Arithmetic, Date and Time, Mathematics, Top @chapter Low-Level Arithmetic Functions @@ -211,6 +217,13 @@ This function returns @code{-1} if @var{x} represents negative infinity, This function returns a nonzero value if @var{x} is a ``not a number'' value, and zero otherwise. (You can just as well use @code{@var{x} != @var{x}} to get the same result). + +However, @code{isnan} will not raise an invalid exception if @var{x} is +a signalling NaN, while @code{@var{x} != @var{x}} will. This makes +@code{isnan} much slower than the alternative; in code where performance +matters and signalling NaNs are unimportant, it's usually better to use +@code{@var{x} != @var{x}}, even though this is harder to understand. + @end deftypefun @comment math.h |