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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
2 | .\" | |
3 | .\" Permission is granted to make and distribute verbatim copies of this | |
4 | .\" manual provided the copyright notice and this permission notice are | |
5 | .\" preserved on all copies. | |
6 | .\" | |
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. | |
11 | .\" | |
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13 | .\" manual page may be incorrect or out-of-date.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 | |
14 | .\" responsibility for errors or omissions, or for damages resulting from | |
15 | .\" the use of the information contained herein. The author(s) may not | |
16 | .\" have taken the same level of care in the production of this manual, | |
17 | .\" which is licensed free of charge, as they might when working | |
18 | .\" professionally. | |
19 | .\" | |
20 | .\" Formatted or processed versions of this manual, if unaccompanied by | |
21 | .\" the source, must acknowledge the copyright and authors of this work. | |
22 | .\" | |
23 | .\" References consulted: | |
24 | .\" Linux libc source code | |
25 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
26 | .\" 386BSD man pages | |
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) | |
30 | .\" | |
31 | .TH FREXP 3 2002-07-27 "" "Linux Programmer's Manual" | |
32 | .SH NAME | |
33 | frexp, frexpf, frexpl \- convert floating-point number to fractional | |
34 | and integral components | |
35 | .SH SYNOPSIS | |
36 | .nf | |
37 | .B #include <math.h> | |
38 | .sp | |
39 | .BI "double frexp(double " x ", int *" exp ); | |
40 | .sp | |
41 | .BI "float frexpf(float " x ", int *" exp ); | |
42 | .sp | |
43 | .BI "long double frexpl(long double " x ", int *" exp ); | |
44 | .fi | |
45 | .sp | |
46 | Link with \-lm. | |
47 | .SH DESCRIPTION | |
48 | The \fBfrexp()\fP function is used to split the number \fIx\fP into a | |
49 | normalized fraction and an exponent which is stored in \fIexp\fP. | |
50 | .SH "RETURN VALUE" | |
51 | The \fBfrexp()\fP function returns the normalized fraction. If the | |
52 | argument \fIx\fP is not zero, the normalized fraction is \fIx\fP | |
53 | times a power of two, and is always in the range 1/2 (inclusive) to | |
54 | 1 (exclusive). If \fIx\fP is zero, then the normalized fraction is | |
55 | zero and zero is stored in \fIexp\fP. | |
56 | .SH "CONFORMING TO" | |
57 | SVID 3, POSIX, BSD 4.3, ISO 9899. | |
58 | The float and the long double variants are C99 requirements. | |
59 | .SH EXAMPLE | |
60 | .nf | |
61 | #include <stdio.h> | |
62 | #include <math.h> | |
63 | #include <float.h> | |
64 | int main () { | |
65 | double d = 2560; | |
66 | int e; | |
67 | double f = frexp(d, &e); | |
68 | printf("frexp(%g, &e) = %g: %g * %d^%d = %g\en", | |
69 | d, f, f, FLT_RADIX, e, d); | |
70 | return 0; | |
71 | } | |
72 | .fi | |
73 | .sp | |
74 | This program prints | |
75 | .sp | |
76 | .in +5 | |
77 | frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560 | |
78 | .in | |
79 | .SH "SEE ALSO" | |
80 | .BR ldexp (3), | |
81 | .BR modf (3) |