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author | bde <bde@FreeBSD.org> | 2005-12-11 17:58:14 +0000 |
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committer | bde <bde@FreeBSD.org> | 2005-12-11 17:58:14 +0000 |
commit | 94455e43e18e7ebc1855d1bc76e56c968da93a10 (patch) | |
tree | adf9ca1a138cb3ea918385a3860d53169ab0d404 /lib | |
parent | 3c8b4e6094d5c1495a556a0e884a9c0e16f97af0 (diff) | |
download | FreeBSD-src-94455e43e18e7ebc1855d1bc76e56c968da93a10.zip FreeBSD-src-94455e43e18e7ebc1855d1bc76e56c968da93a10.tar.gz |
Fixed the unexpectedly large maximum error after the previous commit.
It was because I forgot to translate the part of the double precision
algorithm that chops t so that t*t is exact. Now the maximum error
is the same as for double precision (almost exactly 2.0/3 ulps).
Diffstat (limited to 'lib')
-rw-r--r-- | lib/msun/src/s_cbrtf.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/msun/src/s_cbrtf.c b/lib/msun/src/s_cbrtf.c index 882ed0a..1453ac2 100644 --- a/lib/msun/src/s_cbrtf.c +++ b/lib/msun/src/s_cbrtf.c @@ -67,9 +67,9 @@ cbrtf(float x) /* chop t to 12 bits and make it larger than cbrt(x) */ GET_FLOAT_WORD(high,t); - SET_FLOAT_WORD(t,high+0x00001000); + SET_FLOAT_WORD(t,(high&0xfffff000)+0x00001000); - /* one step Newton iteration to 24 bits with error less than 0.984 ulps */ + /* one step Newton iteration to 24 bits with error less than 0.667 ulps */ s=t*t; /* t*t is exact */ r=x/s; w=t+t; |