Basic Operations (Octave)

Logical operations
1. 1 == 2 1 equals to 2
ans = 0 false

2. 1 ~= 2 1 is not equal to 2
ans = 0 true

3. 1 && 2 AND
ans = 0

4. 1 || 2 OR
ans = 1

5. xor(1,0)
ans = 1

Change default octave prompt: PS1('>> ');

Assign variables
1. a = 3 printing out a = 3

2. a = 3; suppress print out

3. b = 'hi' for strings

4. c = (3>=1) true

Printing
1. disp(a) to show a

2. a = pi
disp(sprintf('2 decimals: %0.2f', a)) 2 decimal places
2 decimals: 3.14

2. disp(sprintf('2 decimals: %0.6f', a)) 6 decimal places
2 decimals: 3.141593

3. format long
a
a = 3.14159265358979

4. format short
a
a = 3.1416

Matrices
1. A = [1 2; 3 4; 5 6] 3 by 2 matrix
$A=\begin{pmatrix}
1 & 2 \\
3 & 4 \\
5 & 6
\end{pmatrix}$

2. v = [1 2 3] 1 by 3 matrix (row vector)
$v=\begin{pmatrix}
1 & 2 & 3
\end{pmatrix}$

3. v = [1; 2; 3] 3 by 1 matrix (column vector)
$v=\begin{pmatrix}
1\\
2\\
3
\end{pmatrix}$

4. v=1:0.1:2 1 by 11 matrix (row vector)
$v=\begin{pmatrix}
1 & 1.1 & 1.2 & … & 1.9 & 2
\end{pmatrix}$

5. v=1:6 1 by 6 matrix (row vector)
$v=\begin{pmatrix}
1 & 2 & 3 & 4 & 5 & 6
\end{pmatrix}$

6. ones(2,3) 2 by 3 matrix of ones
$\begin{pmatrix}
1 & 1 & 1\\
1 & 1 & 1
\end{pmatrix}$

7. 2*ones(2,3)
$\begin{pmatrix}
2 & 2 & 2\\
2 & 2 & 2
\end{pmatrix}$

8. zeros(2,3) 2 by 3 matrix of zeroes
$\begin{pmatrix}
0 & 0 & 0\\
0 & 0 & 0
\end{pmatrix}$

9. rand(2,3) 2 by 3 matrix of random numbers between 0 and 1

10. randn(2,3) 2 by 3 matrix of random numbers drawn from a Gaussian distribution with mean 0 and variance

11. eye(4) 4 by 4 identity matrix
$\begin{pmatrix}
1 & 0 & 0 & 0\\
0 & 1 & 0 & 0\\
0 & 0 & 1 & 0\\
0 & 0 & 0 & 1
\end{pmatrix}$

Plot histogram: w = -6 + sqrt(10)*(randn(1,10000))
hist(w) histogram
hist(w,50) histogram with 50 bins

Help: help rand help function