Update nnbp.m

added rectified linear and softplus activation functions

Author: ericstrobl

NN/nnbp.m

@@ -17,6 +17,11 @@
                 d_act = nn.a{i} .* (1 - nn.a{i});
             case 'tanh_opt'
                 d_act = 1.7159 * 2/3 * (1 - 1/(1.7159)^2 * nn.a{i}.^2);
+            case 'relu'
+                d_act = nn.a{i};
+                d_act(find(d_act>0))=1; d_act(find(d_act<=0))=0;
+            case 'softp'
+                d_act = 1./(1+exp(-nn.a{i}));
         end
 
         if(nn.nonSparsityPenalty>0)