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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) |
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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 | .\" |
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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16 | .\" manual page may be incorrect or out-of-date.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 | .\" |
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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 |
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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 | .\" | |
97986708 | 34 | .TH LDEXP 3 2016-03-15 "" "Linux Programmer's Manual" |
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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> | |
40 | .sp | |
41 | .BI "double ldexp(double " x ", int " exp ); | |
42 | .br | |
43 | .BI "float ldexpf(float " x ", int " exp ); | |
44 | .br | |
45 | .BI "long double ldexpl(long double " x ", int " exp ); | |
46 | .fi | |
47 | .sp | |
20c58d70 | 48 | Link with \fI\-lm\fP. |
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49 | .sp |
50 | .in -4n | |
51 | Feature Test Macro Requirements for glibc (see | |
52 | .BR feature_test_macros (7)): | |
53 | .in | |
54 | .sp | |
55 | .ad l | |
56 | .BR ldexpf (), | |
57 | .BR ldexpl (): | |
b90c43a8 | 58 | .RS 4 |
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59 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
60 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE | |
61 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
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62 | .RE |
63 | .ad | |
fea681da | 64 | .SH DESCRIPTION |
5600f73a | 65 | These functions return the result of multiplying the floating-point number |
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66 | .I x |
67 | by 2 raised to the power | |
68 | .IR exp . | |
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69 | .SH RETURN VALUE |
70 | On success, these functions return | |
71 | .IR "x * (2^exp)" . | |
72 | ||
73 | If | |
74 | .I exp | |
75 | is zero, then | |
76 | .I x | |
77 | is returned. | |
78 | ||
79 | If | |
80 | .I x | |
81 | is a NaN, | |
82 | a NaN is returned. | |
83 | ||
84 | If | |
85 | .I x | |
86 | is positive infinity (negative infinity), | |
87 | positive infinity (negative infinity) is returned. | |
88 | ||
89 | If the result underflows, | |
371b557b | 90 | a range error occurs, |
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91 | and zero is returned. |
92 | ||
93 | If the result overflows, | |
efe294cb | 94 | a range error occurs, |
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95 | and the functions return |
96 | .BR HUGE_VAL , | |
97 | .BR HUGE_VALF , | |
98 | or | |
99 | .BR HUGE_VALL , | |
100 | respectively, with a sign the same as | |
101 | .IR x . | |
102 | .SH ERRORS | |
103 | See | |
104 | .BR math_error (7) | |
105 | for information on how to determine whether an error has occurred | |
106 | when calling these functions. | |
107 | .PP | |
108 | The following errors can occur: | |
109 | .TP | |
110 | Range error, overflow | |
111 | .I errno | |
112 | is set to | |
113 | .BR ERANGE . | |
114 | An overflow floating-point exception | |
115 | .RB ( FE_OVERFLOW ) | |
116 | is raised. | |
117 | .TP | |
118 | Range error, underflow | |
119 | .I errno | |
120 | is set to | |
121 | .BR ERANGE . | |
122 | An underflow floating-point exception | |
123 | .RB ( FE_UNDERFLOW ) | |
124 | is raised. | |
742e3682 | 125 | .SH ATTRIBUTES |
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126 | For an explanation of the terms used in this section, see |
127 | .BR attributes (7). | |
128 | .TS | |
129 | allbox; | |
130 | lbw27 lb lb | |
131 | l l l. | |
132 | Interface Attribute Value | |
133 | T{ | |
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134 | .BR ldexp (), |
135 | .BR ldexpf (), | |
742e3682 | 136 | .BR ldexpl () |
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137 | T} Thread safety MT-Safe |
138 | .TE | |
47297adb | 139 | .SH CONFORMING TO |
9a74e018 | 140 | C99, POSIX.1-2001, POSIX.1-2008. |
e05e3635 | 141 | |
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142 | The variant returning |
143 | .I double | |
144 | also conforms to | |
68e1685c | 145 | SVr4, 4.3BSD, C89. |
47297adb | 146 | .SH SEE ALSO |
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147 | .BR frexp (3), |
148 | .BR modf (3), | |
a57ce78d | 149 | .BR scalbln (3) |