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Introduction to Matlab & Data Analysis

Tutorial time: 3 * one hour sessions:

Wed 11:00-14:00Office hours:

Tue 09:00-10:00Course website:

Tutorial 1: Introduction to Matlab

Environment

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Tutorial Modes Hands off (Most of the tutorial)

Presentation – Repeating lecture material New material

Hands on Examples

Home work submit here Usually two weeks after submission Checkout the course website for updates and

FAQs

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Before we start

Problems If you have computer problems while using the room, please contact:

Irit Orr (#2470) or the WICC PC Helpdesk (#3440).

If you see issues that can be taken care of after your session is over, please contact Irit Orr (#2470) or Ariela Mendel (#3938).

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Before we start Rules of use

Please help us keep the room in good working order.

Do not allow food or drink to be brought into the room

Report problems promptly When leaving the room at the end of a session: Leave the computers on Turn off the projector Turn off all the heating / air conditioning units.

This can be tricky; cup your hand around the end of the remote control to help focus the beam on one unit at a time.

Put the doorstop on the ledge under the whiteboard at the front of the room

Put garbage into the receptacle Turn off all the lights, including the spotlights

that are controlled by the dimmer switch Close the door and make sure that it locks

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Become a Friend of Matlab

Why? It has very attractive visualizations It wants to be your friend:

Very easy to learn Great HELP (!) menu and tutorial Check out the resources in our website.

Very useful: From a simple calculator to complex

data analysis toolbox. Many implemented algorithms.

Great tool for scientific

work.

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Installing Matlab

Classroom Computing supervisor Novel:

Enter to disk Z (username / password) Boris 2443

See instructions on the course web page

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Goals of This Tutorial

1. Familiarizing ourselves with the Matlab Environment

2. Learning basic operations (such as changing

directory)

3. Learning to use Matlab as a simple calculator

4. Writing our first script

5. Learning to use the Help!!!

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Computer Structure - Hardware

Input devices Output devices

Storage devices

CPU Memory

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Computer Structure - Software

Hardware

Gives services to software:

Access input/output devices

Memory allocations

And much more…

Software

Operating system

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From Thoughts to Program

Human language

Matlab language

Intermediate language

Computer language

compiler

I want to add one and one

1+1 mambo-jumbo

010011010011

Operating System

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Matlab - Background

Matlab (Matrix Laboratory) – An interactive program that is suitable

for running computations, drawing graphs and much more (graphical interface).

A programming language for technical computing (scripts).

Lets start…

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Command Window

Command line

Matlab as a calculator:

Lets run our first command:

1 + 1

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Command Window

Previous Command line

The output is displayed

Get the previous command by pressing up arrow keyboard

Can clear window using the command clc

Output (answer)

Current Command line

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Workspace Window

Workspace Window

All workspace variables

Variable value

Demo:

matlab(‘demo’)

http://www.mathworks.com/support/2009b/matlab/7.9/demos/WorkingInTheDevelopmentEnvironment.html

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Command History Window

Command History Window

History

Try drag the command to the command

window

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Matlab Arithmetic Operators

Plus  +

Unary plus  +

Minus -

Unary minus -

multiply *

power ^

Backslash or left matrix divide \

Slash or right matrix divide /

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Matlab Special Numbers

pi 3.14159265…

i and j Imaginary unit

eps Relative precision 2-52

realmin Smallest number 2-1022

realmax Largest number (2-eps)* 21023

Inf Infinity (divide by zero or larger then realmax)

NaN Not a Number (0/0 Inf/Inf)

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Lets Try Matlab as a Calculator

I want to make a fruit salad for 10 people.

Ingredients for 5 people:

6 oranges

5 bananas

3 apples

1 melon

Price list:

orange 1.5

banana 1.2

apple 1

melon 5

What is the total num of fruits needed?

How much will it cost to make the salad?

Answer:

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Lets Try Matlab as a Calculator II

2*5+10

2*(5+10) What does it tell you?

2/3*4

1/0 What did you get?

0/0

1+2+3+4+5+6 Try to use … in order to write in more than one line

2*realmax What did you get?

Try to use:clc , up/down arrow

43231

Usually a Matlab command ends with “;” to disable echo to the command line.

There are 3 ways to display the output: disp() , no “;” fprintf()

Evaluation

Operator evaluation priorities are mathematical(-1+3+2*pi)^(3/4)

Overflow

Inf NaN

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Using the Help

Help: Help (“help cos”); lookfor Doc (“doc cos”); Search F1 / right click Google “matlab …”

“Getting started” Matlab contains many

mathematical functions. Matlab is case

sensitive!

1. Search for “elementary math functions reference” and find the mathematical function reference list

2. How do I calculate “square root” ? Search...

3. What does the function “factor” do?

4. What are the differences between “ceil” “floor”, “fix” and “round”? Try to run “Fix” – what happened?

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Output Format

Use the format function to control the output format of numeric values displayed in the Command Window.

format short (5 digits) , format Long (15 digits) , format rat

Pi = 3.1416, 3.141592653589793 , 355/113

format Compact / format loose – determines the line spacing in the output

Checkout the doc of “format” …

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Current Directory Window

Current Directory

Double click on a file will open it:

.m file (script) in Editor/Debugger

.fig file (figure) in Graphic window

.mat file (data) will load variables to the workspace

Current Directory Window

Files

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Changing The Current Directory

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pwd – current path

cd – change directory

./ - current directory

../ - parent directory

Lets change our directory to our working directory.

We will need to do so on every tutorial start

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Editor / Debugger Window

Open the Editor: Desktop menu -> Editor

F5 / run button

disp(‘hello world’);

You can dock the window

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Set Matlab Search Path Matlab search for scripts and functions in:

Current directory. Path directories.

Can be done also using addpath, rmpath , path etc. Matlab search order:

variables -> keywords -> current directory -> search path.

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Editor / Debugger Window

open Editor: Desktop menu -> Editor

Save your script as helloWorld

run in the command window: helloWorld

More:

Cntrl-C (editor / command win.), Cntrl-V, Cntl-Z, Cntl-F, Cntrl-H

Comments % , %{ this is a comment %}

Case sensitive (and syntax errors)

disp(‘hello world’);

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Handling Errors Errors - Examples: dis(‘error’) ,

disp(‘error): Syntax error in a command Syntax error / Runtime error in a

script

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Desktop Layout Layout – the arrangement of the

windows on the desktop

Any window on the upper right corner

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Standard Toolbar

Help Window Desktop Edit File

More on desktop :

http://www.mathworks.com/support/2007a/matlab/7.4/demos/desktop.html

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A List Of Matlab Operators

Arithmetic operators.     plus       - Plus                                         +     uplus      - Unary plus                               +     minus      - Minus                                      -     uminus     - Unary minus                           -     mtimes     - Matrix multiply                        *     times      - Array multiply                           *     mpower     - Matrix power                          ^     power      - Array power                             .^     mldivide   - Backslash or left matrix divide    \     mrdivide   - Slash or right matrix divide        /     ldivide    - Left array divide                        .\     rdivide    - Right array divide                      ./     kron       - Kronecker tensor product         kron

  Relational operators.     eq         - Equal                                      ==     ne         - Not equal                                 ~=     lt         - Less than                                   <     gt         - Greater than                              >     le         - Less than or equal                     <=     ge         - Greater than or equal                >=

  Logical operators.     and - Logical AND                           &     or         - Logical OR                               |     not       - Logical NOT                            ~     xor       - Logical EXCLUSIVE OR     any      - True if any element of vector is nonzero     all        - True if all elements of vector are nonzero

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Submitting Exercises – documentation and proper coding

% HW_1 solution <HW_# solution>% Yuval Hart 03922881 <name T.Z.> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% short description: % this program calculates and displays the Matlab students grades.% calculation is based on grades in the final exam and a number between % 0.0-2.0 which present the participation of each student in the class.%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% grades = [80 77 70 60 65]; % vector holding the students gradesparticipation_in_class = [1.10, 1.05, 1.07, 0.99, 1.10]; % vector holding the students %participationfinal_grades = (grades .* participation_in_class) + 10; % calculate the students final grades disp(final_grades);

- if (final_grades<60) - for i=1:5- hourly_pay=500*3.62

Magic Numbers:

- if (final_grades<passing_grade)- for i=1:length(students_ID)- hourly_pay=salary*dollarRate