NAME

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

SYNOPSIS

       #include <math.h>

       double ldexp(double x, int exp);
       float ldexpf(float x, int exp);
       long double ldexpl(long double x, int exp);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       ldexpf(), ldexpl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

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

RETURN VALUE

       On success, these functions return x * (2^exp).

       If exp is zero, then x is returned.

       If x is a NaN, a NaN is returned.

       If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned.

       If the result underflows, a range error occurs, and zero is returned.

       If the result overflows, a  range  error  occurs,  and  the  functions  return  HUGE_VAL,  HUGE_VALF,  or
       HUGE_VALL, respectively, with a sign the same as x.

ERRORS

       See  math_error(7)  for  information on how to determine whether an error has occurred when calling these
       functions.

       The following errors can occur:

       Range error, overflow
              errno is set to ERANGE.  An overflow floating-point exception (FE_OVERFLOW) is raised.

       Range error, underflow
              errno is set to ERANGE.  An underflow floating-point exception (FE_UNDERFLOW) is raised.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────┬───────────────┬─────────┐
       │Interface                   │ Attribute     │ Value   │
       ├────────────────────────────┼───────────────┼─────────┤
       │ldexp(), ldexpf(), ldexpl() │ Thread safety │ MT-Safe │
       └────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       C99, POSIX.1-2001, POSIX.1-2008.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO

       frexp(3), modf(3), scalbln(3)

COLOPHON

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       https://www.kernel.org/doc/man-pages/.

                                                   2017-09-15                                           LDEXP(3)