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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. | |
| c13182ef | 11 | .\" |
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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| 13 | .\" manual page may be incorrect or out-of-date.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. | |
| c13182ef | 19 | .\" |
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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 2002-08-10 by Walter Harms (walter.harms@informatik.uni-oldenburg.de) | |
| a1949252 | 29 | .TH COPYSIGN 3 2008-08-05 "GNU" "Linux Programmer's Manual" |
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30 | .SH NAME |
| 31 | copysign, copysignf, copysignl \- copy sign of a number | |
| 32 | .SH SYNOPSIS | |
| 33 | .nf | |
| 34 | .B #include <math.h> | |
| 35 | .sp | |
| 36 | .BI "double copysign(double " x ", double " y ); | |
| 37 | .br | |
| 38 | .BI "float copysignf(float " x ", float " y ); | |
| 39 | .br | |
| 40 | .BI "long double copysignl(long double " x ", long double " y ); | |
| 41 | .fi | |
| 42 | .sp | |
| 20c58d70 | 43 | Link with \fI\-lm\fP. |
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44 | .sp |
| 45 | .in -4n | |
| 46 | Feature Test Macro Requirements for glibc (see | |
| 47 | .BR feature_test_macros (7)): | |
| 48 | .in | |
| 49 | .sp | |
| 50 | .ad l | |
| 51 | .BR copysign (), | |
| e0bf9127 | 52 | .BR copysignf (), |
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53 | .BR copysignl (): |
| 54 | _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or | |
| 55 | .I cc\ -std=c99 | |
| 56 | .ad b | |
| fea681da | 57 | .SH DESCRIPTION |
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58 | The |
| 59 | .BR copysign () | |
| 60 | functions return a value whose absolute value matches | |
| 2f6d6f73 | 61 | that of \fIx\fP, but whose sign bit matches that of \fIy\fP. |
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62 | .SH RETURN VALUE |
| 63 | On success, these functions return a value whose magnitude is taken from | |
| 64 | .I x | |
| 65 | abd whose sign is taken from | |
| 66 | .IR y . | |
| 67 | ||
| 68 | If \fIx\fP is a NaN, | |
| 69 | a NaN with the sign bit of \fIy\fP is returned. | |
| 70 | .SH ERRORS | |
| 71 | No errors occur. | |
| 2b2581ee | 72 | .SH "CONFORMING TO" |
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73 | C99, POSIX.1-2001. |
| 74 | .\" 4.3BSD. | |
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75 | This function is defined in IEC 559 (and the appendix with |
| 76 | recommended functions in IEEE 754/IEEE 854). | |
| fea681da | 77 | .SH NOTES |
| 7981ddab | 78 | On architectures where the floating-point formats are not IEEE 754 compliant, |
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79 | the |
| 80 | .BR copysign () | |
| 81 | functions may treat a negative zero as positive. | |
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82 | .SH "SEE ALSO" |
| 83 | .BR signbit (3) |