Accuracy scores the output as the accuracy of output with respect to target -- it is not actually a loss and has no backward step.

• Layer type: Accuracy
• Doxygen Documentation
• Header: ./include/caffe/layers/accuracy_layer.hpp
• CPU implementation: ./src/caffe/layers/accuracy_layer.cpp

• Parameters (AccuracyParameter accuracy_param)
• From ./src/caffe/proto/caffe.proto):

{% highlight Protobuf %} {% include proto/AccuracyParameter.txt %} {% endhighlight %}