An Introduction to MATLAB Lesson 1

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An Introduction to MATLABLesson 1

• Presenter Andreas Zollmann
• Most of this stuff stolen from
• Dr. Samir Al-Amer

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MATLAB

• MATLABMATrix LABratory
• It is widely used to solve different types of
  scientific problems.
• The basic data structure is a complex double
  precision matrix.

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MATLAB AS A CALCULATOR
Command window
gtgt 394.45 ans 176.6000
Command window
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MATLAB Assignment

• Variable names
• Starts with a letter
• Up to 31 characters ( some use 19 or 21)
• May contain letters, digits and underscore_
• Case sensitive (A is not the same as a)

• A2.3
• A
• 2.3000

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Scalar Assignment
The square braces are used to define
matrices. We can use them for scalars too.

• A2.3
• A
• 2.3000

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Row vector
X2,3 7
X 2 3 7
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Column vector
X23 7
X 2 3 7
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MATLAB Statements
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MATLAB Math Assignment Operators 

• Power  or . ab or   a.b
• Multiplication   or . ab or a.b
• Division / or ./ a/b or a./b
•      or \ or .\ b\a or b.\a
•    NOTE         56/8 8\56 
• - (unary)  (unary)
• Addition      a b
• Subtraction -       a - b
• Assignment    a b     (assign b to a)

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MATLAB Statements
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Help

• A good idea is use the help
• help provides information about the available
  functions and how to use them.
• Try
• help eig
• help inv
• help roots

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Programming in MATLAB

• There are two types of MATLAB programs

script files
function files
script file P1 3 2 roots(P)
function yfun(x) yx23x22
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Programming in MATLABScript files

• A Script file contains a set of MATLAB command
• Use them when you have a long sequence of
  statements to solve a problem
• Can run the program by typing its name in the
  command window or from tools in the editor
  window.

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Relational Operators
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Logical Operators
if (Xgt6) (xlt3)
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Caution! These operators work element-wise

• if A B, statement, end
• does not work as intended!
• ? instead use
• if any(any(A B)), statement, end
• any true iff any element of vector is nonzero
• all true iff all elements of vector are nonzero

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More useful functions

• All of form f(A,dim) by default act on rows
• ones, zeros, max, min, mean, median, sum, prod,
  sort

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If structures

• General form
• If condition
• statements
• else
• statements
• end

If (xgt0) sign1 elseif (x0)
sign0 else sign-1 end
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for loops

• General form
• for indexinitial increment limit
• statements
• end

s0 for i1311 ssi end
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Other cool commands

• A textread('a.txt','n')
• read file containing numbers into vector A
• plot(1n_o_iterations,thetas)
• ezplot('sin(x)',0,10)
• ezplot(sprintf('g(exp(-x/g)-exp(-x/g))',1/(the
  ta1-theta2),theta1,theta2),0,400)
• fh _at_(x,y) (x2y2)
• ezsurfc(fh,0 1)

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Documentation

• Nice easy-to-read introduction
• http//www.andrew.cmu.edu/course/16-720/extras/pr
  imer.pdf
• More stuffhttp//www.mathworks.com/academia/stud
  ent_center/tutorials/launchpad.html