1FREXP(3P)                  POSIX Programmer's Manual                 FREXP(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       frexp, frexpf, frexpl — extract mantissa and  exponent  from  a  double
13       precision number
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SYNOPSIS

16       #include <math.h>
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18       double frexp(double num, int *exp);
19       float frexpf(float num, int *exp);
20       long double frexpl(long double num, int *exp);
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DESCRIPTION

23       The  functionality described on this reference page is aligned with the
24       ISO C standard. Any conflict between the  requirements  described  here
25       and  the  ISO C  standard is unintentional. This volume of POSIX.1‐2017
26       defers to the ISO C standard.
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28       These functions shall break a floating-point number num into a  normal‐
29       ized fraction and an integral power of 2. The integer exponent shall be
30       stored in the int object pointed to by exp.
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RETURN VALUE

33       For finite arguments, these functions shall return the  value  x,  such
34       that  x  has  a  magnitude in the interval [½,1) or 0, and num equals x
35       times 2 raised to the power *exp.
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37       If num is NaN, a NaN shall be  returned,  and  the  value  of  *exp  is
38       unspecified.
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40       If num is ±0, ±0 shall be returned, and the value of *exp shall be 0.
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42       If num is ±Inf, num shall be returned, and the value of *exp is unspec‐
43       ified.
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ERRORS

46       No errors are defined.
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48       The following sections are informative.
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EXAMPLES

51       None.
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APPLICATION USAGE

54       None.
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RATIONALE

57       None.
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FUTURE DIRECTIONS

60       None.
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SEE ALSO

63       isnan(), ldexp(), modf()
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65       The Base Definitions volume of POSIX.1‐2017, <math.h>
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68       Portions of this text are reprinted and reproduced in  electronic  form
69       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
70       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
71       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
72       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
73       event of any discrepancy between this version and the original IEEE and
74       The Open Group Standard, the original IEEE and The Open Group  Standard
75       is  the  referee document. The original Standard can be obtained online
76       at http://www.opengroup.org/unix/online.html .
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78       Any typographical or formatting errors that appear  in  this  page  are
79       most likely to have been introduced during the conversion of the source
80       files to man page format. To report such errors,  see  https://www.ker‐
81       nel.org/doc/man-pages/reporting_bugs.html .
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85IEEE/The Open Group                  2017                            FREXP(3P)
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