hypot(3p) — Linux manual page


HYPOT(3P)               POSIX Programmer's Manual              HYPOT(3P)

PROLOG         top

       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         top

       hypot, hypotf, hypotl — Euclidean distance function

SYNOPSIS         top

       #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         top

       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.1‐2017 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         top

       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

       If both arguments are subnormal and the correct result is
       subnormal, a range error may occur and the correct result shall
       be returned.

ERRORS         top

       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

       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

       The following sections are informative.

EXAMPLES         top

       See the EXAMPLES section in atan2().


       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
       (inexact) 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         top




SEE ALSO         top

       atan2(3p), feclearexcept(3p), fetestexcept(3p), isnan(3p),

       The Base Definitions volume of POSIX.1‐2017, Section 4.20,
       Treatment of Error Conditions for Mathematical Functions,

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                         HYPOT(3P)

Pages that refer to this page: math.h(0p)atan2(3p)