``````

In [3]:

v = zeros(10, 1);  % Column vector

``````
``````

In [5]:

for i=1:10,    % For i in 1 to 10
v(i) = 2^i;
end
v

``````
``````

v =

2
4
8
16
32
64
128
256
512
1024

``````
``````

In [7]:

indexes = 1:10

``````
``````

indexes =

1    2    3    4    5    6    7    8    9   10

``````
``````

In [9]:

for i=indexes, disp(i), end;

``````
``````

1
2
3
4
5
6
7
8
9
10

``````
``````

In [11]:

i = 1;
while i < 5; v(i) = 100; i = i + 1; end;
v

``````
``````

v =

100
100
100
100
32
64
128
256
512
1024

``````
``````

In [12]:

i = 1;
while true,
v(i) = 999;
i = i + 1;
if i == 6,
break;
end;
end;

``````
``````

In [13]:

v(1) = 2;
if v(1) == 1,
disp('the value is one');
elseif v(1) == 2,
disp('the value is two');
else
disp('the value is not one or two');
end;

``````
``````

the value is two

``````
``````

In [14]:

% quit % exit octave

``````

Define a function in a .m file

``````

In [19]:

squareThisNumber(5)  % From squareThisNumber.m

``````
``````

ans =  25

``````
``````

In [20]:

pwd

``````
``````

ans = /home/gary/Devel/python/coursera_ml

``````
``````

In [21]:

``````

Can have functions that return multiple values

``````

In [23]:

[a, b] = squareAndCubeThisNumber(5);
a
b

``````
``````

a =  25
b =  125

``````
``````

In [30]:

X = [1 1; 1 2; 1 3]
y = [1; 2; 3]
theta = [0; 1]

``````
``````

X =

1   1
1   2
1   3

y =

1
2
3

theta =

0
1

``````
``````

In [31]:

j = costfunctionJ(X, y, theta)

``````
``````

sqrErrors =

0
0
0

j = 0

``````
``````

In [33]:

theta = [0;0]
j = costfunctionJ(X, y, theta)

``````
``````

theta =

0
0

sqrErrors =

1
4
9

j =  2.3333

``````
``````

In [35]:

(1^2 + 2^2 + 3^2) / (2 * 3)  % Validate

``````
``````

ans =  2.3333

``````