1. Getting started with Matlab: Outline
What, where and why of matlab.
The matlab desktop and you
Entering commands
Variables and data types
Plotting 101
Saving and loading data
A “real-world” example

2. What is matlab? Scientific programming language
Optimized for working with matrices
Interpolated language = immediate gratification
Learn it in a second, master it in a lifetime
Excellent visualization tools

3. Why NOT to use matlab? To do a single ANOVA!
For applications that absolutely must be super-fast, well written C/Fortran would be quicker (though my C/Fortran would not be).
Low budget. Imitations exist, but usually lack some functionality (octave, scilab, R).
Parallel programming, though some attempts exist to make matlab parallel and some imitations can do parallel programming (scilab).

4. Why use matlab? Modeling, data analysis, image manipulation
Excellent at manipulating large amounts of data with little effort.
Plotting!
Decent set of built-in functions: interpolation, linear algebra, time series, etc.
Lots of free and not so free toolboxes.
Mature language: GUIs, object-oriented programming

5. Where do you get matlab?
University has a site license. Details available at my.ucdavis.edu software channel (contact Tom Fortis and Paul Hirose in EACS)
Advantage: All the toolboxes
Disadvantage: All the toolboxes; generally requires a network connection; have to pay $100-$200 / year
Student version at bookstore for $100
Advantage: For life
Disadvantage: Toolboxes extra, though cheap for students through Mathworks

6. The matlab desktop and you...
Current working directory
Directory listing
List of variables in workspace
Enter commands here
Command history

7. Entering commands
First, change working directory to your student directory.
Commands are entered directly in command window.
1 + 2 * 10
A = pi
B = 2;
C = A + B
Note the difference between the second and third commands – semi-colon at end silences output.
Use Workspace tab or whos command to see defined variables.

8. Getting help
Most matlab functions have excellent and easy to access documentation.
help
help sqrt
helpdesk
Use lookfor command as simple search.
lookfor anova
Other useful commands for looking for help: edit, type, which, more

9. Variables and data types
Matlab figures out variable type all by itself
A = 1
b = A > 1 % This is a boolean
c = 'David'
d = [ 1 2; 3 4 ]
The lines, in order, define a number, boolean, string and array.
Comments start with %
% This does nothing
Get rid of variables with clear
clear c
whos
There are other useful data types in matlab, such as cells and structures (future classes).

10. Array Basics All numbers in matlab are really arrays
d = [ 1 2; 3 4; 5 6 ]
size(A)
size(d)
Getting at array elements:
f = d(1,2)
g = d(:,1) % : used to get a col or row
h = d(2:end,:) % note use of “end”
Creating a list of numbers:
A = 1:5
C = 10:-2:1
Array element-by-element math:
B = A.*A
C = A.^2

11. Plotting 101 Matlab has extremely powerful plotting capabilities
x = -pi:0.1:pi;
y = sin(x);
plot( x, y, 'r' ) % r = red
Add another curve with hold
hold on
plot( x, cos(x).^2, 'b' )
hold off
Adding labels
title( 'Wow!' )
xlabel( 'Time (yr s^{-1})' )
ylabel( 'US Economy' )
Try this:
z = cos(x);
plot( y, z, 'r--', y+1, z, 'b-' )

12. Saving and loading data
The save and load commands do just that:
a = 1; b = 45;
save myvars.mat a b
clear a b
load myvars.mat a
.mat is a binary format that matlab saves data in.
Matlab loads simple text files also:
edit z:\Pkg\WFCB\class1\moms.txt %justlook
load z:\Pkg\WFCB\class1\moms.txt
compass( -moms(:,end-1), -moms(:,end) )
save moms2.txt moms -ASCII
-ASCII tells it to save as a text file.
compass plots arrows (winds in this case).

13. Simple “real world” example
That MOMS data was temperature and wind from BML
load z:\Pkg\WFCB\class1\moms.txt
moms(1:4,:) % Take a look at the data
Make a temperature and alongshore wind plot
plotyy(moms(:,4),moms(:,5), ...
moms(:,4),moms(:,7))
Note how I used “...” to continue command on two lines.

14. Exercises with MOMS data
Exercise1: What is the mean temperature for time period? (hint: Use lookfor to find function to calculate mean)
Exercise2: Calculate correlation between temperature and alongshore wind.
Exercise3: What about lagged correlations? (This is harder, don't worry if you can't do it.)

15. Solution to exercises
The solution can be found in class directory: class1_solutions.m
edit ... z:\Pkg\WFCB\class1\class1_solutions.m
addpath z:\Pkg\WFCB\class1
class1_solutions
% Click on first figure to see second.
The addpath command tells matlab to look for functions and scripts in that directory as well.