BVLC/caffe — pull request #660 by jeffdonahue (2014-07-09 22:11:49+00:00)
Title: Conditionally compute parameter gradients

This lets one use convolution/inner product layers with fixed parameters (i.e. blobs_lr = 0) without unnecessarily computing gradients. It adds a `vector param_propagate_down_` to the layer definition, then net will populate this vector dependent on the `blobs_lr` set for the layer.