Hi!

Thanks for sharing the code!
I have a question regarding to line 79 file bpr.py :
z = 1.0/(1.0+exp(x))

According to the original BPR paper, it seems to me that there should be something like
z = exp(-x)/(1.0+exp(-x))

Am I missing something? Or are those equations proportionally equal?
Thanks,
Ladislav