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Introduction to Matlab forEngineers
Instructor: Thai NhanMath 111, Ohlone, Spring 2016
Introduction to Matlab for Engineers — Ohlone, Spring 2016 1/14
Reminder...
The final is scheduled for Monday May 16,12:00–2:00PM.
Next Test, Monday April 25?
Introduction to Matlab for Engineers — Ohlone, Spring 2016 2/14
Today’s lecture
Other Types of Arrays
Reading material: Chapter 11, Moore’s textbook
Introduction to Matlab for Engineers — Ohlone, Spring 2016 3/14
In addition to the arrays seen in math courses, Matlab canwork with other types of arrays:
Multidimensional arrays
Character arrays
Logical Arrays
Cell Arrays
Structure Arrays
Introduction to Matlab for Engineers — Ohlone, Spring 2016 4/14
Multidimensional Array
A multidimensional array is an array of more than twodimensions. For example, a three-dimensional array can bethought of as a three-dimensional box, or a set of twodimensional arrays stacked together. Accessing the data isdone in the same way as with two dimensional arrays. you cancreate the 2 × 3 × 4 three-dimensional array M of zeros andassign the value 5 to a particular element using
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M=zeros(2,3,4);% three-dimensional array MM(2,1,3)=2016;
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Character Arrays
A character array is how Matlab stores strings. For example,entering the Matlab code x=‘Thai’ will result in a 1 × 4array of type char
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Character Arrays
Since Matlab treats strings as arrays, all the standardMatlab array commands will work. For example, considerthe following
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x=‘Thai’y=‘ loves MATLAB!’% Note the initial spacez=[x,y]
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Introduction to Matlab for Engineers — Ohlone, Spring 2016 7/14
Logical Arrays
A logical array consists of 1s and 0s, where 1 represents a truestatement and 0 represents a false statement. Consider
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a=magic(3)% magic square of size 3b=randi(12,3,3)% Nine random integers 6 12a > b
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Introduction to Matlab for Engineers — Ohlone, Spring 2016 8/14
Cell Arrays
Cell arrays are arrays in which the elements (or cells) mayconsist of different types of data. For example, you canconstruct a 2 × 2 cell array that has the following format.
2(integer) 2.0000(double-precision)Hi!(a string) [2, 3, 4](an array)
Introduction to Matlab for Engineers — Ohlone, Spring 2016 9/14
Cell Arrays
The easiest way to construct a cell array is to construct eachcell separately, and then create the cell array. Note the use of {and } in the final line.
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a=int8(2);b=2;c=‘Hi!’;d=[2,3,4];sample cell=a,b;c,d
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Introduction to Matlab for Engineers — Ohlone, Spring 2016 10/14
Cell Arrays
Cell arrays can also be created directly. In doing so, there aretwo methods of creating the cells. Again note the use of { and}.
Content Addressing a{2, 1} = ‘Hi!’
Cell Indexing a(2, 1) = {‘Hi!’}
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m(1,1)={[2;3;4]};m{1, 2}=[2;3;4];m{2, 1}=‘Hi again!’;m{2, 2}=[2,3;4,5];
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Introduction to Matlab for Engineers — Ohlone, Spring 2016 11/14
Cell Arrays
To get a graphical view of the cell array entercellplot(m)
To see the contents of the cell array, type its name
To see the contents of an element, enter its location.Notice the difference between using content addressinga{2, 1} and cell indexing a(2, 1).
For a full description of cell arrays, look up cell in thedocumentation.
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Structure Arrays
Structures are a type of array that resembles a database file.There is a main name to the structure and then each field hasa name. Each element of the structure array is accessed usinga format like
main name.field name
Introduction to Matlab for Engineers — Ohlone, Spring 2016 13/14
Structure Arrays
Suppose you want to enter the data from the following tableinto Matlab
Room Seats Room Type FurnitureNC-2120 40 lecture tables
FP-7 75 large lecture desksHH-218 24 lab tables
This information can be put into a structure array with threerecords (one for each room) with four fields.
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