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HYPOT(3P)                  POSIX Programmer's Manual                 HYPOT(3P)
PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       hypot, hypotf, hypotl -- Euclidean distance function
SYNOPSIS
       #include <math.h>
       double hypot(double x, double y);
       float hypotf(float x, float y);
       long double hypotl(long double x, long double y);
DESCRIPTION
       The functionality described on this reference page is aligned with  the
       ISO C  standard.  Any  conflict between the requirements described here
       and the ISO C standard is unintentional. This  volume  of  POSIX.1-2008
       defers to the ISO C standard.
       These  functions  shall  compute  the value of the square root of x2+y2
       without undue overflow or underflow.
       An application wishing to check for error situations should  set  errno
       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
       FE_DIVBYZERO  |  FE_OVERFLOW  | FE_UNDERFLOW) is non-zero, an error has
       occurred.
RETURN VALUE
       Upon successful completion, these functions shall return the length  of
       the hypotenuse of a right-angled triangle with sides of length x and y.
       If  the  correct  value would cause overflow, a range error shall occur
       and hypot(), hypotf(), and hypotl() shall return the value of the macro
       HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
       If  x  or  y is +-Inf, +Inf shall be returned (even if one of x or y is
       NaN).
       If x or y is NaN, and the other is not +-Inf, a NaN shall be returned.
       If both arguments are subnormal and the correct result is subnormal,  a
       range error may occur and the correct result shall be returned.
ERRORS
       These functions shall fail if:
       Range Error The result overflows.
                   If  the  integer expression (math_errhandling & MATH_ERRNO)
                   is non-zero, then errno shall be set to [ERANGE].   If  the
                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
                   non-zero, then the overflow floating-point exception  shall
                   be raised.
       These functions may fail if:
       Range Error The result underflows.
                   If  the  integer expression (math_errhandling & MATH_ERRNO)
                   is non-zero, then errno shall be set to [ERANGE].   If  the
                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
                   non-zero, then the underflow floating-point exception shall
                   be raised.
       The following sections are informative.
EXAMPLES
       See the EXAMPLES section in atan2().
APPLICATION USAGE
       hypot(x,y), hypot(y,x), and hypot(x, -y) are equivalent.
       hypot(x, +-0) is equivalent to fabs(x).
       Underflow  only  happens when both x and y are subnormal and the (inex-
       act) result is also subnormal.
       These functions take precautions against overflow  during  intermediate
       steps of the computation.
       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
       at least one of them must be non-zero.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       atan2(), feclearexcept(), fetestexcept(), isnan(), sqrt()
       The Base Definitions volume of POSIX.1-2008, Section 4.19, Treatment of
       Error Conditions for Mathematical Functions, <math.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.unix.org/online.html .
       Any  typographical  or  formatting  errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files  to  man page format. To report such errors, see https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                            HYPOT(3P)