]>
Commit | Line | Data |
---|---|---|
fea681da | 1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
a57ce78d MK |
2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
fea681da | 4 | .\" |
93015253 | 5 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
6 | .\" Permission is granted to make and distribute verbatim copies of this |
7 | .\" manual provided the copyright notice and this permission notice are | |
8 | .\" preserved on all copies. | |
9 | .\" | |
10 | .\" Permission is granted to copy and distribute modified versions of this | |
11 | .\" manual under the conditions for verbatim copying, provided that the | |
12 | .\" entire resulting derived work is distributed under the terms of a | |
13 | .\" permission notice identical to this one. | |
c13182ef | 14 | .\" |
fea681da MK |
15 | .\" Since the Linux kernel and libraries are constantly changing, this |
16 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
17 | .\" responsibility for errors or omissions, or for damages resulting from | |
18 | .\" the use of the information contained herein. The author(s) may not | |
19 | .\" have taken the same level of care in the production of this manual, | |
20 | .\" which is licensed free of charge, as they might when working | |
21 | .\" professionally. | |
c13182ef | 22 | .\" |
fea681da MK |
23 | .\" Formatted or processed versions of this manual, if unaccompanied by |
24 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 25 | .\" %%%LICENSE_END |
fea681da MK |
26 | .\" |
27 | .\" References consulted: | |
28 | .\" Linux libc source code | |
29 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
30 | .\" 386BSD man pages | |
31 | .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) | |
32 | .\" Modified 2004-10-31 by aeb | |
33 | .\" | |
4b8c67d9 | 34 | .TH LDEXP 3 2017-09-15 "" "Linux Programmer's Manual" |
fea681da MK |
35 | .SH NAME |
36 | ldexp, ldexpf, ldexpl \- multiply floating-point number by integral power of 2 | |
37 | .SH SYNOPSIS | |
38 | .nf | |
39 | .B #include <math.h> | |
68e4db0a | 40 | .PP |
fea681da | 41 | .BI "double ldexp(double " x ", int " exp ); |
fea681da | 42 | .BI "float ldexpf(float " x ", int " exp ); |
fea681da MK |
43 | .BI "long double ldexpl(long double " x ", int " exp ); |
44 | .fi | |
68e4db0a | 45 | .PP |
20c58d70 | 46 | Link with \fI\-lm\fP. |
68e4db0a | 47 | .PP |
a57ce78d MK |
48 | .in -4n |
49 | Feature Test Macro Requirements for glibc (see | |
50 | .BR feature_test_macros (7)): | |
51 | .in | |
68e4db0a | 52 | .PP |
a57ce78d MK |
53 | .ad l |
54 | .BR ldexpf (), | |
55 | .BR ldexpl (): | |
b90c43a8 | 56 | .RS 4 |
e9d91bcf MK |
57 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
58 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE | |
59 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
b90c43a8 MK |
60 | .RE |
61 | .ad | |
fea681da | 62 | .SH DESCRIPTION |
5600f73a | 63 | These functions return the result of multiplying the floating-point number |
fea681da MK |
64 | .I x |
65 | by 2 raised to the power | |
66 | .IR exp . | |
a57ce78d MK |
67 | .SH RETURN VALUE |
68 | On success, these functions return | |
69 | .IR "x * (2^exp)" . | |
847e0d88 | 70 | .PP |
a57ce78d MK |
71 | If |
72 | .I exp | |
73 | is zero, then | |
74 | .I x | |
75 | is returned. | |
847e0d88 | 76 | .PP |
a57ce78d MK |
77 | If |
78 | .I x | |
79 | is a NaN, | |
80 | a NaN is returned. | |
847e0d88 | 81 | .PP |
a57ce78d MK |
82 | If |
83 | .I x | |
84 | is positive infinity (negative infinity), | |
85 | positive infinity (negative infinity) is returned. | |
847e0d88 | 86 | .PP |
a57ce78d | 87 | If the result underflows, |
371b557b | 88 | a range error occurs, |
a57ce78d | 89 | and zero is returned. |
847e0d88 | 90 | .PP |
a57ce78d | 91 | If the result overflows, |
efe294cb | 92 | a range error occurs, |
a57ce78d MK |
93 | and the functions return |
94 | .BR HUGE_VAL , | |
95 | .BR HUGE_VALF , | |
96 | or | |
97 | .BR HUGE_VALL , | |
98 | respectively, with a sign the same as | |
99 | .IR x . | |
100 | .SH ERRORS | |
101 | See | |
102 | .BR math_error (7) | |
103 | for information on how to determine whether an error has occurred | |
104 | when calling these functions. | |
105 | .PP | |
106 | The following errors can occur: | |
107 | .TP | |
108 | Range error, overflow | |
109 | .I errno | |
110 | is set to | |
111 | .BR ERANGE . | |
112 | An overflow floating-point exception | |
113 | .RB ( FE_OVERFLOW ) | |
114 | is raised. | |
115 | .TP | |
116 | Range error, underflow | |
117 | .I errno | |
118 | is set to | |
119 | .BR ERANGE . | |
120 | An underflow floating-point exception | |
121 | .RB ( FE_UNDERFLOW ) | |
122 | is raised. | |
742e3682 | 123 | .SH ATTRIBUTES |
23514ee4 MK |
124 | For an explanation of the terms used in this section, see |
125 | .BR attributes (7). | |
126 | .TS | |
127 | allbox; | |
128 | lbw27 lb lb | |
129 | l l l. | |
130 | Interface Attribute Value | |
131 | T{ | |
742e3682 PH |
132 | .BR ldexp (), |
133 | .BR ldexpf (), | |
742e3682 | 134 | .BR ldexpl () |
23514ee4 MK |
135 | T} Thread safety MT-Safe |
136 | .TE | |
47297adb | 137 | .SH CONFORMING TO |
9a74e018 | 138 | C99, POSIX.1-2001, POSIX.1-2008. |
847e0d88 | 139 | .PP |
a57ce78d MK |
140 | The variant returning |
141 | .I double | |
142 | also conforms to | |
68e1685c | 143 | SVr4, 4.3BSD, C89. |
47297adb | 144 | .SH SEE ALSO |
fea681da MK |
145 | .BR frexp (3), |
146 | .BR modf (3), | |
a57ce78d | 147 | .BR scalbln (3) |