# MatlabIntro

From CCRMA Wiki

## Basics

- Use semi-colon at the end of the line to prevent the output of the operation to be printed to the screen

- Comments are specified using % at the beginning of the comment. Only line comments are allowed (sorry, but no block-comments, although there's a shortcut in the editor to comment out all the selected lines)

% This is a comment x = 0; % this is another comment

- The "language" is not strongly typed. The following sequence is valid:

x = 1; x = "this is a string"

- Functions may return more than one value, and they can be of any type. For example:

[r,c] = size([ones(2)])

## Vector and Matrices

- Use square brackets to define a vector/matrix

x = [1 2 3 4 5]

- Inside a vector/matrix definition, commas or spaces separate elements row-wise. For example:

x = [1 2 3 4 5]

is the same as:

x = [1,2,3,4,5]

and they both generate a row vector. Semi-colons, instead, separate elements column-wise. For example, the following line will create a column vector:

x = [1;2;3;4;5]

- You can combine both to create a matrix:

x = [1 2 3 4;2 3 4 5;3 4 5 6]

- Some useful vector/matrix operators are:

The following code snippets assume that x was defined as:

x = [1 2;3 4]

- Use ' as a suffix to transpose the vector/matrix:

>> x' ans = 1 3 2 4 >>

- The function size(x) will return the size of x: first number is the number of row and the second is the number of columns:

>> size(x) ans = 2 2

- You can access individual elements of a matrix using parenthesis (first argument specifies the row and the second specifies the column):

>> x(2,1) ans = 3

## Plotting

The basic command is plot(x), to plot the contents of x (if x is a matrix, then each column is plotted as a different line):

fs = 441000; t = 0:1/fs:0.01; plot(sin(2*pi*220*t));

You can also use plot(x,y):

plot(t, sin(2*pi*220*t));

By default plot will erase the previous plot before drawing the new one. Use hold to prevent this from happening. Also, you can use a third argument to specify the line color (and other plotting options):

hold on; plot(t, sin(2*pi*110*t), 'r'); plot(t, sin(2*pi*330*t), 'g'); plot(t, sin(2*pi*440*t), 'k'); hold off

## Sound

## General tips

- Try to vectorize every operation if you can