diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128/x2y2m1l.c')
-rw-r--r-- | sysdeps/ieee754/ldbl-128/x2y2m1l.c | 76 |
1 files changed, 0 insertions, 76 deletions
diff --git a/sysdeps/ieee754/ldbl-128/x2y2m1l.c b/sysdeps/ieee754/ldbl-128/x2y2m1l.c deleted file mode 100644 index d3f88331b5..0000000000 --- a/sysdeps/ieee754/ldbl-128/x2y2m1l.c +++ /dev/null @@ -1,76 +0,0 @@ -/* Compute x^2 + y^2 - 1, without large cancellation error. - Copyright (C) 2012-2017 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library 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 2.1 of the License, or (at your option) any later version. - - The GNU C Library 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 the GNU C Library; if not, see - <http://www.gnu.org/licenses/>. */ - -#include <math.h> -#include <math_private.h> -#include <mul_splitl.h> -#include <stdlib.h> - - -/* Calculate X + Y exactly and store the result in *HI + *LO. It is - given that |X| >= |Y| and the values are small enough that no - overflow occurs. */ - -static inline void -add_split (_Float128 *hi, _Float128 *lo, _Float128 x, _Float128 y) -{ - /* Apply Dekker's algorithm. */ - *hi = x + y; - *lo = (x - *hi) + y; -} - -/* Compare absolute values of floating-point values pointed to by P - and Q for qsort. */ - -static int -compare (const void *p, const void *q) -{ - _Float128 pld = fabsl (*(const _Float128 *) p); - _Float128 qld = fabsl (*(const _Float128 *) q); - if (pld < qld) - return -1; - else if (pld == qld) - return 0; - else - return 1; -} - -/* Return X^2 + Y^2 - 1, computed without large cancellation error. - It is given that 1 > X >= Y >= epsilon / 2, and that X^2 + Y^2 >= - 0.5. */ - -_Float128 -__x2y2m1l (_Float128 x, _Float128 y) -{ - _Float128 vals[5]; - SET_RESTORE_ROUNDL (FE_TONEAREST); - mul_splitl (&vals[1], &vals[0], x, x); - mul_splitl (&vals[3], &vals[2], y, y); - vals[4] = -1; - qsort (vals, 5, sizeof (_Float128), compare); - /* Add up the values so that each element of VALS has absolute value - at most equal to the last set bit of the next nonzero - element. */ - for (size_t i = 0; i <= 3; i++) - { - add_split (&vals[i + 1], &vals[i], vals[i + 1], vals[i]); - qsort (vals + i + 1, 4 - i, sizeof (_Float128), compare); - } - /* Now any error from this addition will be small. */ - return vals[4] + vals[3] + vals[2] + vals[1] + vals[0]; -} |