Name
nan, nanf, nanl — return 'Not a Number'
Synopsis
#include <math.h>
double nan( |
const char * |
tagp) ; |
float
nanf( |
const char * |
tagp) ; |
long
double nanl( |
const char * |
tagp) ; |
![[Note]](../stylesheet/note.png) |
Note |
Feature
Test Macro Requirements for glibc (see
feature_test_macros(7)): |
nan (),
nanf (),
nanl (): |
_XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE ; |
or cc -std=c99 |
|
![[Note]](../stylesheet/note.png) |
Note |
Compile with −std=c99 ; link with
−lm .
|
DESCRIPTION
These functions return a representation (determined by
tagp
) of a quiet NaN.
If the implementation does not support quiet NaNs, these
functions return zero.
The call nan("char-sequence")
is
equivalent to strtod
("NAN(char-sequence)",NULL) and similarly calls
to nanf
() and nanl
() are equivalent to analogous calls to
strtof(3) and strtold(3).
The argument tagp
is used in an unspecified manner. On IEEE 754 systems, there
are many representations of NaN, and tagp
selects one. On other
systems it may do nothing.
CONFORMING TO
C99. See also IEC 559 and the appendix with recommended
functions in IEEE 754/IEEE 854.
SEE ALSO
isnan(3), strtod(3)
Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
Distributed under GPL
Based on glibc infopages
Corrections by aeb
|