Lecture 6                                                   Sept 15, 09
Download
1 / 37

Lecture 6 Sept 15, 09 Goals: - PowerPoint PPT Presentation


  • 121 Views
  • Uploaded on

Lecture 6 Sept 15, 09 Goals: two-dimensional arrays matrix operations circuit analysis using Matlab image processing – simple examples. 4.2. Matrices Example: The following 2 x 3 matrix (matA) can be created in Matlab as follows:.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Lecture 6 Sept 15, 09 Goals:' - claudia-gay


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  • Lecture 6 Sept 15, 09

  • Goals:

  • two-dimensional arrays

  • matrix operations

  • circuit analysis using Matlab

  • image processing – simple examples


4.2. Matrices Sept 15, 09

Example: The following 2 x 3 matrix (matA) can be created in Matlab as follows:

Dimension of a matrix can be accessed by function called size.





Matrix operations Sept 15, 09

Matrix addition, multiplication, inverse, determinant etc.


Matrix operations Sept 15, 09

Matrix addition, multiplication, inverse, determinant, transpose etc.



Exercise: Solve a linear system of equations: Sept 15, 09

3x + 5y – 6z= 11

4x – 6y + z = 9

-2x + 3y + 5z = –13


Example 2 Sept 15, 09



4.3. Mixed Data Types Sept 15, 09

Structure is variable that can hold a group of data (of different types).

Example:


Array of structures Sept 15, 09

Example:


Cell arrays Sept 15, 09

A cell array is like a vector, except that each member need not be all of the same type.


Images as arrays Sept 15, 09


Images as arrays Sept 15, 09

Numerical representation of

array (gray scale image)

Visual representation



Selecting a subimage Sept 15, 09

Just like we can copy a part of an array into another array, we can copy a part of one image and create a new image.




image rotation Sept 15, 09

Exercise: Write a one-line statement in Matlab that will rotate an image by 180 degrees.


image rotation Sept 15, 09

Exercise: Write a one-line statement in Matlab that will rotate an image by 180 degrees.


image rotation Sept 15, 09

Exercise: Write a one-line statement in Matlab that will rotate an image by 180 degrees.

>> J = I(size(I,1):-1:1, :, :);


Discussions and exercises, Chapter 4 Sept 15, 09

Exercise 4.1


  • Exercise 4.2 Sept 15, 09

  • Write statements to do the following operations on a vector x:

  • Return the odd indexed elements.


Exercise 4.2 Sept 15, 09

Write statements to do the following operations on a vector x:

2) Return the first half of x.


Exercise 4.2 Sept 15, 09

Write statements to do the following operations on a vector x:

3) Return the vector in the reverse order.


Exercise 4.3 Sept 15, 09

Given a vector v, and a vector k of indices, write a one or two statement code in Matlab that removes the elements of v in positions specified by k.

Example:

>> v = [1, 3, 5, 7, 11, 9, 19]

>> k = [2, 4, 5]

>> < your code here>

>> v

ans =

1, 5, 9, 19


Exercise 4.3 Sept 15, 09

Given a vector v, and a vector k of indices, write a one or two statement code in Matlab that removes the elements of v in positions specified by k.


Exercise 4.4 what does Matlab output for the following commands?

1) 6 ~= 1 : 10

2) (6 ~= 1) : 10


Exercise 4.4 what does Matlab output for the following commands?

1) 6 ~= 1 : 10

2) (6 ~= 1) : 10


Exercise 4.5. (This is a bit tricky, especially without using a loop construct like while or for.)

Write a statement to return the elements of a vector randomly shuffled.

Hint provided is a useful one.

First understand how sort function works.


Reshaping arrays
Reshaping Arrays using a loop construct like

  • Arrays are actually stored in column order in Matlab. So internally, a 2 × 3 array is stored as a column vector:A(1,1)

    A(2,1)

    A(1,2)

    A(2,2)

    A(1,3)

    A(2,3)

  • Any n × m array can be reshaped into any p × q array as long as n*m = p*q using the reshape function.


Summary
Summary using a loop construct like

This chapter introduced you to vectors and arrays. For each collection, you saw how to:

■ Create them by concatenation and a variety of special-purpose functions

■ Access and remove elements, rows, or columns

■ Perform mathematical and logical operations on them

■ Apply library functions, including those that summarize whole columns or rows

■ Move arbitrary selected rows and columns from one array to another

■ image – how to create them, open them, change etc.


ad