diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c | 26 |
1 files changed, 10 insertions, 16 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c b/sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c index a001b58ca5..da2e929175 100644 --- a/sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c +++ b/sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c @@ -1,5 +1,5 @@ /* Compute x^2 + y^2 - 1, without large cancellation error. - Copyright (C) 2012-2015 Free Software Foundation, Inc. + Copyright (C) 2012-2016 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 @@ -80,13 +80,13 @@ compare (const void *p, const void *q) } /* Return X^2 + Y^2 - 1, computed without large cancellation error. - It is given that 1 > X >= Y >= epsilon / 2, and that either X >= - 0.75 or Y >= 0.5. */ + It is given that 1 > X >= Y >= epsilon / 2, and that X^2 + Y^2 >= + 0.5. */ long double __x2y2m1l (long double x, long double y) { - double vals[12]; + double vals[13]; SET_RESTORE_ROUND (FE_TONEAREST); union ibm_extended_long_double xu, yu; xu.ld = x; @@ -105,25 +105,19 @@ __x2y2m1l (long double x, long double y) vals[8] *= 2.0; vals[9] *= 2.0; mul_split (&vals[11], &vals[10], yu.d[1].d, yu.d[1].d); - if (xu.d[0].d >= 0.75) - vals[1] -= 1.0; - else - { - vals[1] -= 0.5; - vals[7] -= 0.5; - } - qsort (vals, 12, sizeof (double), compare); + vals[12] = -1.0; + qsort (vals, 13, sizeof (double), 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 <= 10; i++) + for (size_t i = 0; i <= 11; i++) { add_split (&vals[i + 1], &vals[i], vals[i + 1], vals[i]); - qsort (vals + i + 1, 11 - i, sizeof (double), compare); + qsort (vals + i + 1, 12 - i, sizeof (double), compare); } /* Now any error from this addition will be small. */ - long double retval = (long double) vals[11]; - for (size_t i = 10; i != (size_t) -1; i--) + long double retval = (long double) vals[12]; + for (size_t i = 11; i != (size_t) -1; i--) retval += (long double) vals[i]; return retval; } |