92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
/* Hypotenuse of a right-angled triangle.
|
|
Copyright (C) 2012-2024 Free Software Foundation, Inc.
|
|
|
|
This file is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as
|
|
published by the Free Software Foundation, either version 3 of the
|
|
License, or (at your option) any later version.
|
|
|
|
This file is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with this program. If not, see <https://www.gnu.org/licenses/>. */
|
|
|
|
/* Written by Bruno Haible <bruno@clisp.org>, 2012. */
|
|
|
|
#include <config.h>
|
|
|
|
/* Specification. */
|
|
#include <math.h>
|
|
|
|
#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
|
|
|
|
long double
|
|
hypotl (long double x, long double y)
|
|
{
|
|
return hypot (x, y);
|
|
}
|
|
|
|
#else
|
|
|
|
long double
|
|
hypotl (long double x, long double y)
|
|
{
|
|
if (isfinite (x) && isfinite (y))
|
|
{
|
|
/* Determine absolute values. */
|
|
x = fabsl (x);
|
|
y = fabsl (y);
|
|
|
|
{
|
|
/* Find the bigger and the smaller one. */
|
|
long double a;
|
|
long double b;
|
|
|
|
if (x >= y)
|
|
{
|
|
a = x;
|
|
b = y;
|
|
}
|
|
else
|
|
{
|
|
a = y;
|
|
b = x;
|
|
}
|
|
/* Now 0 <= b <= a. */
|
|
|
|
{
|
|
int e;
|
|
long double an;
|
|
long double bn;
|
|
|
|
/* Write a = an * 2^e, b = bn * 2^e with 0 <= bn <= an < 1. */
|
|
an = frexpl (a, &e);
|
|
bn = ldexpl (b, - e);
|
|
|
|
{
|
|
long double cn;
|
|
|
|
/* Through the normalization, no unneeded overflow or underflow
|
|
will occur here. */
|
|
cn = sqrtl (an * an + bn * bn);
|
|
return ldexpl (cn, e);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (isinf (x) || isinf (y))
|
|
/* x or y is infinite. Return +Infinity. */
|
|
return HUGE_VALL;
|
|
else
|
|
/* x or y is NaN. Return NaN. */
|
|
return x + y;
|
|
}
|
|
}
|
|
|
|
#endif
|