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86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/* Pythagorean addition using doubles
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Copyright (C) 2011-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library
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Contributed by Adhemerval Zanella <azanella@br.ibm.com>, 2011
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_private.h>
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#include <math-underflow.h>
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#include <stdint.h>
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/* __ieee754_hypot(x,y)
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*
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* This a FP only version without any FP->INT conversion.
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* It is similar to default C version, making appropriates
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* overflow and underflows checks as well scaling when it
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* is needed.
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*/
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double
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__ieee754_hypot (double x, double y)
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{
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if ((isinf (x) || isinf (y))
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&& !issignaling (x) && !issignaling (y))
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return INFINITY;
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if (isnan (x) || isnan (y))
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return x + y;
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x = fabs (x);
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y = fabs (y);
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if (y > x)
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{
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double t = x;
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x = y;
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y = t;
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}
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if (y == 0.0)
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return x;
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/* if y is higher enough, y * 2^60 might overflow. The tests if
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y >= 1.7976931348623157e+308/2^60 (two60factor) and uses the
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appropriate check to avoid the overflow exception generation. */
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if (y <= 0x1.fffffffffffffp+963 && x > (y * 0x1p+60))
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return x + y;
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if (x > 0x1p+500)
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{
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x *= 0x1p-600;
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y *= 0x1p-600;
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return sqrt (x * x + y * y) / 0x1p-600;
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}
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if (y < 0x1p-500)
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{
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if (y <= 0x0.fffffffffffffp-1022)
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{
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x *= 0x1p+1022;
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y *= 0x1p+1022;
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double ret = sqrt (x * x + y * y) / 0x1p+1022;
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math_check_force_underflow_nonneg (ret);
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return ret;
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}
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else
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{
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x *= 0x1p+600;
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y *= 0x1p+600;
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return sqrt (x * x + y * y) / 0x1p+600;
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}
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}
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return sqrt (x * x + y * y);
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}
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strong_alias (__ieee754_hypot, __hypot_finite)
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