1. MATH 493 Introduction to MATLAB

2. MATLAB MATLAB is run as an interactive program
You type a command, MATLAB responds with an answer; repeat
MATLAB processing is based largely on array and matrix manipulations

3. MATLAB Interface

4. Basic Usage Enter simple calculations at the command prompt
Define variables at the command prompt
Use cursor keys to revisit previous commands
Use first letters and cursor keys for more control

5. Editor Use File/New/Blank M-file to create a script file
store a sequence of commands for later use
editor does automatic highlighting
necessary for anything more than toy examples

6. Further Commands Standard mathematical functions are built in:
cos, sin, log, log10, exp
Suppress output with semi-colon
User variable names should be different from built-in functions, variables
File/Clear Workspace (or type ‘clear’) to clear all variables

7. Matrices and MATLAB (Nearly) all MATLAB variables are matrices
scalars are 1x1 matrices
vectors are 1xn or nx1 matrices
‘size’ function gives dimensions of a matrix

8. Manually Creating Matrices
Use square brackets
v = [1 3 10]
Semi-colons separate rows
v = [1; 3; 10]
Sometimes easier to write using matrix transpose, ’. Compare
v = [1 3 10]’

9. Functions for Creating Matrices 1
Colon operator
1:5 - same as [ ]
1:0.1:2 - counts by 0.1 from 1 to 2
linspace
linspace(10,50, 1000) - counts from 10 to 50 using 1000 points
linspace(10,50) - counts from 10 to 50 using (default) 100 points. Often used for quick graphs

10. Functions for Creating Matrices 2
ones
ones(3) - creates 3x3 matrix of ones
ones(4,1) - creates 4x1 vector of ones
zeros
zeros(3) - creates 3x3 matrix of zeros
zeros(4,5) - creates 4x5 matrix of zeros
eye - (for “Identity”)
eye(3) - creates 3x3 identity matrix

11. This is not C
Many MATLAB functions can take in single arguments or matrices
Using a matrix is often faster and more clear
Plotting example - graph of cosine
x = linspace(0, 6*pi)
y = cos(x)
plot(x, y)

12. Plot Command Requirements
‘plot’ will generate an x vs y plot when given two equal-length vectors
The plot will appear in a new window
There are many plotting options; some are included in the activities

13. Matrix Problems! Try the following plot of a quadratic
x = linspace(-2, 2)
y = x^2
plot(x, y)
Very common problem in course!
x^2 means….
x.^2 means….

14. Continuing Try the exercises on the sheet.
Look at the output each time to make sure you understand what each command is doing!