ldexp(3) - f30

1LDEXP(3)                   Linux Programmer's Manual                  LDEXP(3)
2
3
4

NAME

6       ldexp,  ldexpf,  ldexpl  -  multiply  floating-point number by integral
7       power of 2
8

SYNOPSIS

10       #include <math.h>
11
12       double ldexp(double x, int exp);
13       float ldexpf(float x, int exp);
14       long double ldexpl(long double x, int exp);
15
16       Link with -lm.
17
18   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
19
20       ldexpf(), ldexpl():
21           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
22               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
23               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
24

DESCRIPTION

26       These functions return the result  of  multiplying  the  floating-point
27       number x by 2 raised to the power exp.
28

RETURN VALUE

30       On success, these functions return x * (2^exp).
31
32       If exp is zero, then x is returned.
33
34       If x is a NaN, a NaN is returned.
35
36       If x is positive infinity (negative infinity), positive infinity (nega‐
37       tive infinity) is returned.
38
39       If the result underflows, a range error occurs, and zero is returned.
40
41       If the result overflows, a range error occurs, and the functions return
42       HUGE_VAL,  HUGE_VALF,  or HUGE_VALL, respectively, with a sign the same
43       as x.
44

ERRORS

46       See math_error(7) for information on how to determine whether an  error
47       has occurred when calling these functions.
48
49       The following errors can occur:
50
51       Range error, overflow
52              errno  is  set  to ERANGE.  An overflow floating-point exception
53              (FE_OVERFLOW) is raised.
54
55       Range error, underflow
56              errno is set to ERANGE.  An underflow  floating-point  exception
57              (FE_UNDERFLOW) is raised.
58

ATTRIBUTES

60       For   an   explanation   of   the  terms  used  in  this  section,  see
61       attributes(7).
62
63       ┌────────────────────────────┬───────────────┬─────────┐
64       │Interface                   │ Attribute     │ Value   │
65       ├────────────────────────────┼───────────────┼─────────┤
66       │ldexp(), ldexpf(), ldexpl() │ Thread safety │ MT-Safe │
67       └────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

69       C99, POSIX.1-2001, POSIX.1-2008.
70
71       The variant returning double also conforms to SVr4, 4.3BSD, C89.
72

COLOPHON

77       This page is part of release 4.16 of the Linux  man-pages  project.   A
78       description  of  the project, information about reporting bugs, and the
79       latest    version    of    this    page,    can     be     found     at
80       https://www.kernel.org/doc/man-pages/.
81
82
83
84                                  2017-09-15                          LDEXP(3)