title: What's the difference between Softmax and SoftmaxWithLoss layer in caffe?
body: <p>While defining <code>prototxt</code> in caffe, I found sometimes we use <code>Softmax</code> as the last layer type, sometimes we use <code>SoftmaxWithLoss</code>, I know the <code>Softmax</code> layer will return the probability the input data belongs to each class, but it seems that <code>SoftmaxwithLoss</code> will also return the class probability, then what's the difference between them? or did I misunderstand the usage of the two layer types?</p>