title: Tensorflow loss function?
body: <p>There are many loss functions in tensorflow like sigmoid_cross_entropy_logits, softmax_cross_entropy_logits. Could you please write mathematical formulations of these functions? And what is logits? Is it referring to <a href="https://en.wikipedia.org/wiki/Logit" rel="nofollow">this</a> function? And is it applied element wise?</p>