1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
3 .\" Permission is granted to make and distribute verbatim copies of this
4 .\" manual provided the copyright notice and this permission notice are
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7 .\" Permission is granted to copy and distribute modified versions of this
8 .\" manual under the conditions for verbatim copying, provided that the
9 .\" entire resulting derived work is distributed under the terms of a
10 .\" permission notice identical to this one.
12 .\" Since the Linux kernel and libraries are constantly changing, this
13 .\" manual page may be incorrect or out-of-date. The author(s) assume no
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15 .\" the use of the information contained herein. The author(s) may not
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17 .\" which is licensed free of charge, as they might when working
20 .\" Formatted or processed versions of this manual, if unaccompanied by
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23 .\" References consulted:
24 .\" Linux libc source code
25 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
27 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
28 .\" Modified 2002-07-27 by Walter Harms
29 .\" (walter.harms@informatik.uni-oldenburg.de)
31 .TH FREXP 3 2002-07-27 "" "Linux Programmer's Manual"
33 frexp, frexpf, frexpl \- convert floating-point number to fractional
34 and integral components
39 .BI "double frexp(double " x ", int *" exp );
41 .BI "float frexpf(float " x ", int *" exp );
43 .BI "long double frexpl(long double " x ", int *" exp );
50 function is used to split the number \fIx\fP into a
51 normalized fraction and an exponent which is stored in \fIexp\fP.
55 function returns the normalized fraction.
56 If the argument \fIx\fP is not zero,
57 the normalized fraction is \fIx\fP times a power of two,
58 and its absolute value is always in the range 1/2 (inclusive) to
60 If \fIx\fP is zero, then the normalized fraction is
61 zero and zero is stored in \fIexp\fP.
68 variants are C99 requirements.
77 main(int argc, char *argv[])
82 x = strtod(argv[1], NULL);
85 printf("frexp(%g, &e) = %g: %g * %d^%d = %g\\n",
86 x, r, r, FLT_RADIX, exp, x);
91 This program produces results such as the following:
95 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
97 frexp(\-4, &e) = \-0.5: \-0.5 * 2^3 = -4