frexp, frexpf, frexpl — convert floating-point number to fractional and integral components
||long double x,|
These functions are used to split the number
x into a normalized fraction
and an exponent which is stored in
These functions return the normalized fraction. If the
x is not
zero, the normalized fraction is
x times a power of two, and its
absolute value is always in the range 1/2 (inclusive) to 1
(exclusive), that is, [0.5,1).
x is zero, then
the normalized fraction is zero and zero is stored in
x is a NaN, a
NaN is returned, and the value of *
exp is unspecified.
x is positive
infinity (negative infinity), positive infinity (negative
infinity) is returned, and the value of *
exp is unspecified.
For an explanation of the terms used in this section, see attributes(7).
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
The program below produces results such as the following:
$ ./a.out 2560 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560 $ ./a.out −4 frexp(−4, &e) = −0.5: −0.5 * 2^3 = −4
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Copyright 1993 David Metcalfe (davidprism.demon.co.uk)
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Linux libc source code
Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
386BSD man pages
Modified 1993-07-24 by Rik Faith (faithcs.unc.edu)
Modified 2002-07-27 by Walter Harms