Additional sigmoid from Apurva, non-square costFunction

ex2/test_costfunction_forums.m

@@ -0,0 +1,20 @@
+function test_costfunction_forums ()
+  epsilon = 1e-4;
+
+  % CTA Colin Beckingham
+  % https://class.coursera.org/ml-005/forum/thread?thread_id=943#post-4641
+  [J grad] = costFunction([0 1 0]', magic(3), [1 2 3]');
+  assert( J, -7.5600, epsilon );
+  assert( grad, [-4.3907 -7.7678 -4.2202]', epsilon);
+
+
+  % Me - non-square matrix example
+  % I HAVE NOT VALIDATE THIS BY HAND
+  % https://class.coursera.org/ml-005/forum/thread?thread_id=943#comment-3379
+  X = magic(3)(1:2,:)
+  [J grad] = costFunction([1 2 3]', X, [4 5]');
+  assert( J, -109.93, 1e-2 );
+  assert( grad, [-18.000 -11.500 -23.000]', 1e-2);
+
+
+endfunction

ex2/test_ex2.m

@@ -6,6 +6,8 @@
 
 %!test test_costfunction_nontrivial()
 
+%!test test_costfunction_forums()
+
 %!test test_predict()
 
 %!test test_costfunction_reg_minimal()

ex2/test_sigmoid.m

@@ -29,7 +29,12 @@ function test_sigmoid ()
   %
   % Apurva Dubey
   %
-  assert(sigmoid([1 2 3]), [0.73106 0.88080 0.95257], 1e-4);
-  assert(sigmoid([4 -2 -3]), [0.98201 0.119203 0.047426], 1e-4);
+  epsilon = 1e-4;
+  assert(sigmoid([1 2 3]), [0.73106 0.88080 0.95257], epsilon);
+  assert(sigmoid([4 -2 -3]), [0.98201 0.119203 0.047426], epsilon);
 
+  % https://class.coursera.org/ml-005/forum/thread?thread_id=943#comment-3352
+  assert( sigmoid([-1.414 2.739 -3.1415 pi sin(pi/2)]), 
+    [0.195604 0.939289 0.041428 0.958576 0.731059 ], epsilon );
+
 endfunction