ISNORMAL(3P) POSIX Programmer's Manual ISNORMAL(3P)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.
NAMEisnormal — test for a normal value
int isnormal(real-floating x);
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.1‐2008
defers to the ISO C standard.
The isnormal() macro shall determine whether its argument value is nor‐
mal (neither zero, subnormal, infinite, nor NaN). First, an argument
represented in a format wider than its semantic type is converted to
its semantic type. Then determination is based on the type of the argu‐
The isnormal() macro shall return a non-zero value if and only if its
argument has a normal value.
No errors are defined.
The following sections are informative.
SEE ALSOfpclassify(), isfinite(), isinf(), isnan(), signbit()
The Base Definitions volume of POSIX.1‐2008, <math.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
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IEEE/The Open Group 2013 ISNORMAL(3P)