Anomaly in mpn_sqrtrem and mpn_rootrem
Marco Bodrato
bodrato at mail.dm.unipi.it
Wed Aug 19 05:55:59 UTC 2015
Ciao,
On Tue, August 18, 2015 10:51 am, Torbjörn Granlund wrote:
> I miss some rootrem logs from ChangeLog.
Before the changes I just pushed, I simply reordered the steps in the loop
to shorten the first and the last iteration in the loop...
> How much speed difference is there now, for k = 4 vs sqrt(sqrt())?
mpn_sqrt mpn_root.4 mpn_root.8 mpn_root.16
1 #33.86 659.37 229.62 178.01
2 #112.47 916.25 789.81 273.80
4 #245.35 1350.10 1111.97 1117.45
8 #419.01 1934.60 1683.93 1570.81
16 #1015.91 2611.44 2558.12 2472.39
32 #1666.53 3837.72 3969.28 4031.27
64 #3305.67 6295.23 6160.25 6654.23
> Is the difference small enough that we could fix it by running the first
> few iterations using plain limb arithmetic?
I fear it is not.
--
http://bodrato.it/
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