Subject: Performance of the logarithm algorithm on bfloats
From: Raymond Toy
Date: Mon, 26 Apr 2010 00:29:05 -0400
On 4/25/10 11:21 PM, Richard Fateman wrote:
> I wonder if you are noticing the time used to convert this number to
> base 10, and depending on what front end you are using,
> this could be done a smart way or not.
>
No, It's not the time to convert the number. The original routine,
fplog, is still in the sources, and (fplog <test value>) takes a very
long time. It's not surprising since the algorithm divides the test
value by %e until it's near one. Since the test value is about
2b31455787102040073147561, it's no surprise this takes a long time.
Ray