ldexp(3) - f39

1ldexp(3)                   Library Functions 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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LIBRARY

10       Math library (libm, -lm)
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SYNOPSIS

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

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

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

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

61       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
62       tributes(7).
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64       ┌────────────────────────────────────────────┬───────────────┬─────────┐
65       │Interface                                   │ Attribute     │ Value   │
66       ├────────────────────────────────────────────┼───────────────┼─────────┤
67       │ldexp(), ldexpf(), ldexpl()                 │ Thread safety │ MT-Safe │
68       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

71       C11, POSIX.1-2008.
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HISTORY

74       C99, POSIX.1-2001.
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76       The variant returning double also conforms to SVr4, 4.3BSD, C89.
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