[Bug-gnubg] Possible error in SSE sigmoid calculation

[Philippe Michel]

In lib/sigmoid.h, there is some code to calculate quickly exp(x) including 
the statement :
i = (int)x1;

In lib/neuralnetsse.c, the corresponding SSE code is :
i.i  = _mm_cvtps_epi32( x1 );

Shouldn't that be _mm_cvttps_epi32( x1 ) ? The cast-to-int truncates, it 
doesn't round, does it ?

Amazingly (to me, at least), it apparently makes very little difference in 
the final net outputs but the current code seems erroneous.