Merge pull request #8 from ratiopharm88/master

I tried doing the NN stuff today

handin3/Code/NNMarco/backprop.m

@@ -0,0 +1,44 @@
+function [delta der] = backprop (w, z, a, targety, layers)
+layersum=cumsum(layers);
+
+%delta=zeros(1, layersum(length(layersum))-layersum(1));
+delta=zeros(1, layersum(length(layersum)));
+
+der=zeros(size(w));
+
+%for i=layersum(length(layersum)):-1:(layersum(1)+1)
+for i=layersum(length(layersum)):-1:1
+    %% if it is an output neuron
+    if (i>layersum(length(layersum)-1))
+       %delta(i-layersum(1)) = z(i+1)-targety(i-layersum(length(layersum)-1));
+       delta(i) = z(i+1)-targety(i-layersum(length(layersum)-1));
+    else
+        ai=a(i+1);
+        ha=1/((1+abs(ai))^2);
+
+        sum=0;
+        for k=i+1:layersum(length(layersum))
+            sum=sum+delta(k)*w(k,i+1);
+        end
+
+        delta(i) = ha * sum;
+    end
+end
+
+%% compute the partial derivatives
+
+for i=1:1:layersum(length(layersum))
+
+%     if i<layersum(1)+1
+%         for j=0:1:layersum(length(layersum))
+%             der(i,j+1)=delta(i-layersum(1)) * z(j+1); 
+%         end
+%     else
+        for j=0:1:layersum(length(layersum))
+            der(i,j+1)=delta(i) * z(j+1); 
+        end
+%    end
+end
+
+
+end

handin3/Code/NNMarco/nn.m

@@ -0,0 +1,43 @@
+function [z a] = nn(w, layers, inputs)
+layernos=cumsum(layers);
+
+%% set z0 to 1
+%% z must be treated as zero-based
+z=ones(1, size(w,2));
+a=zeros(1, size(w,2));
+
+%% input equals output for input neurons
+for i=1:layers(1)
+   z(i+1)=inputs(i);
+end
+
+%% for each hidden and output neuron
+%% i is the neuron number
+for i=(layernos(1)+1):size(w,1)
+    sum=0;
+    first=1;
+    %% find first neuron of this layer
+    for j=2:length(layernos)
+        if i<=layernos(j)
+            first=layernos(j-1)+1;
+        end
+    end
+
+    %% iterate over all input neurons
+
+    for j=0:(first-1)
+       sum=sum+z(j+1)*w(i, j+1);
+    end
+
+    a(i+1)=sum;
+
+    %% for output neurons, output is linear, otherwise use the function.
+    if (i<=layernos(length(layernos)-1))
+        z(i+1)=sum/(1+abs(sum));
+    else
+        z(i+1)=sum;
+    end
+end
+
+
+end