mirror of https://github.com/mkerrisk/man-pages
155 lines
3.9 KiB
Groff
155 lines
3.9 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.\" manual page may be incorrect or out-of-date.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 2002-07-27 by Walter Harms
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.\" (walter.harms@informatik.uni-oldenburg.de)
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.\"
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.TH HYPOT 3 2008-08-05 "" "Linux Programmer's Manual"
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.SH NAME
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hypot, hypotf, hypotl \- Euclidean distance function
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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 hypot(double " x ", double " y );
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.br
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.BI "float hypotf(float " x ", float " y );
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.br
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.BI "long double hypotl(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 hypot ():
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.br
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.BR hypotf (),
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.BR hypotl ():
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_BSD_SOURCE || _SVID_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 hypot ()
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function returns
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.RI sqrt( x * x + y * y ).
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This is the length of the hypotenuse of a right-angled triangle
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with sides of length
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.I x
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and
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.IR y ,
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or the distance of the point
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.RI ( x , y )
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from the origin.
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The calculation is performed without undue overflow or underflow
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during the intermediate steps of the calculation.
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.\" e.g., hypot(DBL_MIN, DBL_MIN) does the right thing, as does, say
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.\" hypot(DBL_MAX/2.0, DBL_MAX/2.0).
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.SH RETURN VALUE
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On success, these functions return the length of a right-angled triangle
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with sides of length
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.I x
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and
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.IR y .
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If
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.I x
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or
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.I y
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is an infinity,
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positive infinity is returned.
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If
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.I x
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or
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.I y
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is a NaN,
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and the other argument is not an infinity,
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a NaN is returned.
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If the result overflows,
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a range error occurs,
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and the functions return
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.BR HUGE_VAL ,
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.BR HUGE_VALF ,
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or
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.BR HUGE_VALL ,
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respectively.
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If both arguments are subnormal, and the result is subnormal,
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.\" Actually, could the result not be subnormal if both arguments
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.\" are subnormal? I think not -- mtk, Jul 2008
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a range error occurs,
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and the correct result is returned.
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.SH ERRORS
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See
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.BR math_error (7)
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for information on how to determine whether an error has occurred
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when calling these functions.
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.PP
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The following errors can occur:
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.TP
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Range error: result overflow
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.I errno
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is set to
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.BR ERANGE .
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An overflow floating-point exception
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.RB ( FE_OVERFLOW )
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is raised.
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.TP
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Range error: result underflow
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.\" .I errno
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.\" is set to
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.\" .BR ERANGE .
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An underflow floating-point exception
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.RB ( FE_UNDERFLOW )
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is raised.
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.IP
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These functions do not set
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.IR errno
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for this case.
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.\" FIXME . Is it intentional that these functions do not set errno?
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.\" They do set errno for the overflow case.
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.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6795
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.SH "CONFORMING TO"
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C99, POSIX.1-2001.
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The variant returning
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.I double
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also conforms to
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SVr4, 4.3BSD.
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.SH "SEE ALSO"
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.BR cabs (3),
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.BR sqrt (3)
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