Finished task 3

calculate_hypothesis.m

@@ -1,9 +1,10 @@
 function hypothesis = calculate_hypothesis(X, theta, training_example)
     %CALCULATE_HYPOTHESIS This calculates the hypothesis for a given X,
     %theta and specified training example
-    x = X(training_example, 1:length(theta));
-
-    hypothesis = sum(x.*theta);
-    %hypothesis = theta(1)*x0+theta(2)*x1+theta(3)*x2;
+    x = X(training_example, 1:2);
+    
+    %hypothesis = sum(x.*theta);
+    %
+    hypothesis = theta(1)*x(1)+theta(2)*x(2)+theta(3)*x(2)^2+theta(4)*x(2)^3+theta(5)*x(2)^4+theta(6)*x(2)^5;
 end
 

gradient_descent.m

@@ -1,4 +1,4 @@
-function theta = gradient_descent(X, y, theta, alpha, iterations, do_plot)
+function theta = gradient_descent(X, y, theta, alpha, iterations, l, do_plot)
     %GRADIENT_DESCENT do Gradient Descent for a given X, y, theta, alpha
     %for a specified number of iterations
 
@@ -31,14 +31,20 @@ function theta = gradient_descent(X, y, theta, alpha, iterations, do_plot)
                 sigma = sigma + (hypothesis - output) * X(i, ind);
             end
 
-            theta_temp(ind) = theta_temp(ind) - ((alpha * 1.0) / m) * sigma;
+            % theta_temp(ind) = theta_temp(ind) - ((alpha * 1.0) / m) * sigma;
+            if ind > 1
+                theta_temp(ind) = (theta_temp(ind) * (1.0-alpha*(l/m))) - ((alpha * 1.0) / m) * sigma;
+            else
+                theta_temp(ind) = theta_temp(ind) - ((alpha * 1.0) / m) * sigma;
+            end
+
         end
 
         %update theta
         theta = theta_temp;
 
         %update cost_vector
-        cost_vector = [cost_vector; compute_cost(X, y, theta)];
+        cost_vector = [cost_vector; compute_cost_regularised(X, y, theta, l)];
 
         if do_plot
             plot_hypothesis(X, y, theta);

mllab3.m

@@ -14,10 +14,10 @@ function mllab3()
     end
 
     % initialise theta
-    theta = [1.0, 1.0, 1.0, 1.0, 1.0];
+    theta = [1.0, 1.0, 1.0, 1.0, 1.0, 1.0];
 
-    alpha = 0.01;
-    l = 0.0;
+    alpha = 1.0;
+    l = 3;
     iterations = 1000;
     do_plot = false;
 
@@ -57,4 +57,4 @@ function hypothesis = get_hypothesis(x, theta)
     for t = 1:length(theta)
         hypothesis = hypothesis + theta(t) * (x ^ (t - 1));
     end
-end
+end