[Bug-gnubg] sse and sigmoid bug

[Joseph Heled]

Hi,

While "importing" the sse code to gnubg-nn I discovered an error in the sigmoid implementation. The calculation made by the see code did not match the one from the straight C code. (It was relatively easy for me to catch since sse can be toggled during run time in gnubg-nn)

Since this results in bad evaluations, I am surprised it has not been detected in gnubg.

Has anyone did a real side-by-side comparison of gnubg with sse enabled and disabled?

I would not like to make changes to gnubg, but encourage the people responsible for the sse code to have a look at gnubg-nn and see if they agree.

-Joseph