from numpy import log
def cross_entropy(y, a):
return -1*(y*log(a) + (1-y)*log(1-a))
cross_entropy(1, 0.9997)
0.00030004500900199243
cross_entropy(1, 0.9)
0.10536051565782628
cross_entropy(1, 0.6)
0.5108256237659907
cross_entropy(1, 0.1192)
2.1269525243508878
cross_entropy(0, 0.1192)
0.1269246935736668
cross_entropy(1, 1-0.1192)
0.1269246935736668