1HYPOT(P)                   POSIX Programmer's Manual                  HYPOT(P)
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NAME

6       hypot, hypotf, hypotl - Euclidean distance function
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SYNOPSIS

9       #include <math.h>
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11       double hypot(double x, double y);
12       float hypotf(float x, float y);
13       long double hypotl(long double x, long double y);
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15

DESCRIPTION

17       These  functions  shall  compute  the value of the square root of x**2+
18       y**2 without undue overflow or underflow.
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20       An application wishing to check for error situations should  set  errno
21       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
22       functions.  On return, if errno is non-zero or  fetestexcept(FE_INVALID
23       |  FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
24       occurred.
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RETURN VALUE

27       Upon successful completion, these functions shall return the length  of
28       the hypotenuse of a right-angled triangle with sides of length x and y.
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30       If  the  correct  value would cause overflow, a range error shall occur
31       and hypot(), hypotf(), and hypotl() shall return the value of the macro
32       HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
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34       If  x  or  y  is ±Inf, +Inf shall be returned (even if one of x or y is
35       NaN).
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37       If x or y is NaN, and the other is not ±Inf, a NaN shall be returned.
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39       If both arguments are subnormal and the correct result is subnormal,  a
40       range error may occur and the correct result is returned.
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ERRORS

43       These functions shall fail if:
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45       Range Error
46              The result overflows.
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48       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
49       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
50       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then the overflow
51       floating-point exception shall be raised.
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54       These functions may fail if:
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56       Range Error
57              The result underflows.
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59       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
60       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
61       (math_errhandling & MATH_ERREXCEPT) is  non-zero,  then  the  underflow
62       floating-point exception shall be raised.
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65       The following sections are informative.
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EXAMPLES

68       None.
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APPLICATION USAGE

71       hypot(x,y), hypot(y,x), and hypot(x, -y) are equivalent.
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73       hypot(x, ±0) is equivalent to fabs(x).
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75       Underflow  only  happens when both x and y are subnormal and the (inex‐
76       act) result is also subnormal.
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78       These functions take precautions against overflow  during  intermediate
79       steps of the computation.
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81       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
82       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
83       at least one of them must be non-zero.
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RATIONALE

86       None.
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FUTURE DIRECTIONS

89       None.
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SEE ALSO

92       feclearexcept()  , fetestexcept() , isnan() , sqrt() , the Base Defini‐
93       tions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of  Error
94       Conditions for Mathematical Functions, <math.h>
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97       Portions  of  this text are reprinted and reproduced in electronic form
98       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
99       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
100       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
101       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
102       event of any discrepancy between this version and the original IEEE and
103       The  Open Group Standard, the original IEEE and The Open Group Standard
104       is the referee document. The original Standard can be  obtained  online
105       at http://www.opengroup.org/unix/online.html .
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109IEEE/The Open Group                  2003                             HYPOT(P)
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