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authorPetr Baudis <pasky@suse.cz>2011-09-09 22:16:10 -0400
committerUlrich Drepper <drepper@gmail.com>2011-09-09 22:16:10 -0400
commit1248c1c41508387ff282b208636737e8cdc9b5b0 (patch)
treef2de6f410de805293483964814aa29efefbe8daa /sysdeps/ieee754/ldbl-128ibm
parentf19009c1551a396ee8eff96a83254243ce25a090 (diff)
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Fix jn precision
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm')
-rw-r--r--sysdeps/ieee754/ldbl-128ibm/e_jnl.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_jnl.c b/sysdeps/ieee754/ldbl-128ibm/e_jnl.c
index 0eea745..372f942 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_jnl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_jnl.c
@@ -286,7 +286,16 @@ __ieee754_jnl (n, x)
}
}
}
- b = (t * __ieee754_j0l (x) / b);
+ /* j0() and j1() suffer enormous loss of precision at and
+ * near zero; however, we know that their zero points never
+ * coincide, so just choose the one further away from zero.
+ */
+ z = __ieee754_j0l (x);
+ w = __ieee754_j1l (x);
+ if (fabsl (z) >= fabsl (w))
+ b = (t * z / b);
+ else
+ b = (t * w / a);
}
}
if (sgn == 1)