mirror of https://github.com/mkerrisk/man-pages
74 lines
2.5 KiB
Groff
74 lines
2.5 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 2002-08-10 by Walter Harms (walter.harms@informatik.uni-oldenburg.de)
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.TH COPYSIGN 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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copysign, copysignf, copysignl \- copy sign of a number
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.SH SYNOPSIS
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.nf
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.B #include <math.h>
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.sp
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.BI "double copysign(double " x ", double " y );
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.br
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.BI "float copysignf(float " x ", float " y );
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.br
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.BI "long double copysignl(long double " x ", long double " y );
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.fi
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.sp
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Link with \fI-lm\fP.
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR copysign (),
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.BR copysignf (),
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.BR copysignl ():
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_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.ad b
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.SH DESCRIPTION
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The
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.BR copysign ()
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functions return a value whose absolute value matches
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that of \fIx\fP, but whose sign matches that of \fIy\fP.
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If \fIx\fP is a NaN, then a NaN with the sign of \fIy\fP is returned.
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.SH "CONFORMING TO"
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C99, 4.3BSD.
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This function is defined in IEC 559 (and the appendix with
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recommended functions in IEEE 754/IEEE 854).
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.SH NOTES
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On architectures where the floating-point formats are not IEEE 754 compliant,
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the
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.BR copysign ()
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functions may treat a negative zero as positive.
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.SH "SEE ALSO"
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.BR signbit (3)
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