вернуть тихо NaN (return quiet NaN)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
nan, nanf, nanl — return quiet NaN
Синопсис (Synopsis)
#include <math.h>
double nan(const char *tagp);
float nanf(const char *tagp);
long double nanl(const char *tagp);
Описание (Description)
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
The function call nan("n-char-sequence") shall be equivalent to:
strtod("NAN(n-char-sequence)", (char **) NULL);
The function call nan("") shall be equivalent to:
strtod("NAN()", (char **) NULL)
If tagp does not point to an n-char sequence or an empty string,
the function call shall be equivalent to:
strtod("NAN", (char **) NULL)
Function calls to nanf() and nanl() are equivalent to the
corresponding function calls to strtof() and strtold().
Возвращаемое значение (Return value)
These functions shall return a quiet NaN, if available, with
content indicated through tagp.
If the implementation does not support quiet NaNs, these
functions shall return zero.
Ошибки (Error)
No errors are defined.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
strtod(3p)
The Base Definitions volume of POSIX.1‐2017, math.h(0p)
