man3/hypot.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  30 .\" Modified 2002-07-27 by Walter Harms
  31 .\"     (walter.harms@informatik.uni-oldenburg.de)
  32 .\"
  33 .TH HYPOT 3 2017-09-15 ""  "Linux Programmer's Manual"
  34 .SH NAME
  35 hypot, hypotf, hypotl \- Euclidean distance function
  36 .SH SYNOPSIS
  37 .nf
  38 .B #include <math.h>
  39 .PP
  40 .BI "double hypot(double " x ", double " y );
  41 .BI "float hypotf(float " x ", float " y );
  42 .BI "long double hypotl(long double " x ", long double " y );
  43 .fi
  44 .PP
  45 Link with \fI\-lm\fP.
  46 .PP
  47 .in -4n
  48 Feature Test Macro Requirements for glibc (see
  49 .BR feature_test_macros (7)):
  50 .in
  51 .PP
  52 .ad l
  53 .BR hypot ():
  54 .RS 4
  55 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  56     || _XOPEN_SOURCE
  57     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  58     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  59 .RE
  60 .br
  61 .BR hypotf (),
  62 .BR hypotl ():
  63 .RS 4
  64 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  65     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  66     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  67 .RE
  68 .ad b
  69 .SH DESCRIPTION
  70 These functions return
  71 .RI sqrt( x * x + y * y ).
  72 This is the length of the hypotenuse of a right-angled triangle
  73 with sides of length
  74 .I x
  75 and
  76 .IR y ,
  77 or the distance of the point
  78 .RI ( x , y )
  79 from the origin.
  80 .PP
  81 The calculation is performed without undue overflow or underflow
  82 during the intermediate steps of the calculation.
  83 .\" e.g., hypot(DBL_MIN, DBL_MIN) does the right thing, as does, say
  84 .\" hypot(DBL_MAX/2.0, DBL_MAX/2.0).
  85 .SH RETURN VALUE
  86 On success, these functions return the length of a right-angled triangle
  87 with sides of length
  88 .I x
  89 and
  90 .IR y .
  91 .PP
  92 If
  93 .I x
  94 or
  95 .I y
  96 is an infinity,
  97 positive infinity is returned.
  98 .PP
  99 If
 100 .I x
 101 or
 102 .I y
 103 is a NaN,
 104 and the other argument is not an infinity,
 105 a NaN is returned.
 106 .PP
 107 If the result overflows,
 108 a range error occurs,
 109 and the functions return
 110 .BR HUGE_VAL ,
 111 .BR HUGE_VALF ,
 112 or
 113 .BR HUGE_VALL ,
 114 respectively.
 115 .PP
 116 If both arguments are subnormal, and the result is subnormal,
 117 .\" Actually, could the result not be subnormal if both arguments
 118 .\" are subnormal?  I think not -- mtk, Jul 2008
 119 a range error occurs,
 120 and the correct result is returned.
 121 .SH ERRORS
 122 See
 123 .BR math_error (7)
 124 for information on how to determine whether an error has occurred
 125 when calling these functions.
 126 .PP
 127 The following errors can occur:
 128 .TP
 129 Range error: result overflow
 130 .I errno
 131 is set to
 132 .BR ERANGE .
 133 An overflow floating-point exception
 134 .RB ( FE_OVERFLOW )
 135 is raised.
 136 .TP
 137 Range error: result underflow
 138 .\" .I errno
 139 .\" is set to
 140 .\" .BR ERANGE .
 141 An underflow floating-point exception
 142 .RB ( FE_UNDERFLOW )
 143 is raised.
 144 .IP
 145 These functions do not set
 146 .IR errno
 147 for this case.
 148 .\" FIXME . Is it intentional that these functions do not set errno?
 149 .\" They do set errno for the overflow case.
 150 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6795
 151 .SH ATTRIBUTES
 152 For an explanation of the terms used in this section, see
 153 .BR attributes (7).
 154 .TS
 155 allbox;
 156 lbw27 lb lb
 157 l l l.
 158 Interface       Attribute       Value
 159 T{
 160 .BR hypot (),
 161 .BR hypotf (),
 162 .BR hypotl ()
 163 T}      Thread safety   MT-Safe
 164 .TE
 165 .sp 1
 166 .SH CONFORMING TO
 167 C99, POSIX.1-2001, POSIX.1-2008.
 168 .PP
 169 The variant returning
 170 .I double
 171 also conforms to
 172 SVr4, 4.3BSD.
 173 .SH SEE ALSO
 174 .BR cabs (3),
 175 .BR sqrt (3)