ldexp(3)

1LDEXP(3)                   Linux Programmer's Manual                  LDEXP(3)
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NAME

6       ldexp,  ldexpf,  ldexpl  -  multiply  floating-point number by integral
7       power of 2
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SYNOPSIS

10       #include <math.h>
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12       double ldexp(double x, int exp);
13       float ldexpf(float x, int exp);
14       long double ldexpl(long double x, int exp);
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16       Link with -lm.
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18   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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20       ldexpf(), ldexpl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
21       || _ISOC99_SOURCE; or cc -std=c99
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DESCRIPTION

24       The  ldexp()  function  returns the result of multiplying the floating-
25       point number x by 2 raised to the power exp.
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RETURN VALUE

28       On success, these functions return x * (2^exp).
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30       If exp is zero, then x is returned.
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32       If x is a NaN, a NaN is returned.
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34       If x is positive infinity (negative infinity), positive infinity (nega‐
35       tive infinity) is returned.
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37       If the result underflows, an  range error occurs, and zero is returned.
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39       If the result overflows, a range error occurs, and the functions return
40       HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with a sign  the  same
41       as x.
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ERRORS

44       See  math_error(7) for information on how to determine whether an error
45       has occurred when calling these functions.
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47       The following errors can occur:
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49       Range error, overflow
50              errno is set to ERANGE.  An  overflow  floating-point  exception
51              (FE_OVERFLOW) is raised.
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53       Range error, underflow
54              errno  is  set to ERANGE.  An underflow floating-point exception
55              (FE_UNDERFLOW) is raised.
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CONFORMING TO

58       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
59       4.3BSD, C89.
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COLOPHON

65       This  page  is  part of release 3.22 of the Linux man-pages project.  A
66       description of the project, and information about reporting  bugs,  can
67       be found at http://www.kernel.org/doc/man-pages/.
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71                                  2008-08-05                          LDEXP(3)