From 821cfec80bb6a6c20831c09ed977b63d6fbd59d2 Mon Sep 17 00:00:00 2001
From: Yuichiro Someya <ayemos.y@gmail.com>
Date: Sun, 8 May 2016 11:42:21 +0900
Subject: [PATCH] Vectorize correctly.

---
 mlclass-ex1-005/mlclass-ex1/computeCost.m | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mlclass-ex1-005/mlclass-ex1/computeCost.m b/mlclass-ex1-005/mlclass-ex1/computeCost.m
index c5afbc1..6885c9a 100644
--- a/mlclass-ex1-005/mlclass-ex1/computeCost.m
+++ b/mlclass-ex1-005/mlclass-ex1/computeCost.m
@@ -19,10 +19,9 @@
 %end;
 
 % Vectorized implementation
-J = sum(((X * theta) - y) .^ 2);
-
-J = 1 / (2 * m) * J;
+Z = (X * theta) - y;
+J = (Z' * Z) / (2 * m);
 
 % =========================================================================
 
-end
\ No newline at end of file
+end