# Basic Matlab

Matlab is the most powerful example of numerical linear algebra software. It has some symbolic capabilities, but here we describe only the most basic aspects of matrix and vector handling. Simple examples of these procedures follow.

- Define row vector:

`x=[1 2 3 4 5]` - Define column vector:

`y=[1`

2

3

4

5]

or

`y=[1;2;3;4;5]` - Vector multiplication:

`x*y`gives 55;`y*x`gives a 5×5 matrix. - Elementwise multiplication and exponentiation:

`[1 2] .* [1 2]`gives`[1 4]`

`[1 2] .^ 2`gives`[1 4]` - Define matrix:

`A = [1 2`

3 4]

or

`A=[1 2; 3 4]` - Transpose of a matrix or vector

`A'` - Multiplication:

`A*[1;2]` - Subtraction:

`x-y'` - Matrix inverse:

`inv(A)` - Identity matrix of dimension N:

`eye(N)` - Zero matrix of dimension m by n:

`zeros(m,n)` - Constant matrix of dimension m by n

`anumber * ones(m,n)` - Previous commands: use the up-arrow key to get commands entered earlier. Use the left arrow and backspace keys to move and delete from those commands, so you can modify them.
- Variable list: the
`who`command lists all the variables that are currently defined. - Help: typing
`help commandname`gives a page of help about the command called`commandname.`

Assignment 6 is posted.

The midterm exam will take place on Friday,
12 October. As always, you are permitted any paper
notes you find useful, but no electronic devices are
allowed. The test is cumulative, but emphasizes
the material covered in the last fours weeks.
A sample exam is
available.

You need to install
Matlab
on your computer by Wednesday.
You do not need Simulink or any particular toolboxes, though
you might find the Symbolic toolbox useful at some time
in the future (not in this class).