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MATLAB FUNDAMENTALS: MATRIX/ARRAY FUNCTIONS THE COLON MATRIX/ARRAY MANIPULATION I NPUT/ O UTPUT

MATLAB FUNDAMENTALS: MATRIX/ARRAY FUNCTIONS THE COLON MATRIX/ARRAY MANIPULATION I NPUT/ O UTPUT. HP 100 – MATLAB Wednesday, 9/3/2014 www.clarkson.edu/class/honorsmatlab. Before We Begin:. Any Questions? Comments? Concerns? Feel free to contact Joe or Jim

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MATLAB FUNDAMENTALS: MATRIX/ARRAY FUNCTIONS THE COLON MATRIX/ARRAY MANIPULATION I NPUT/ O UTPUT

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  1. MATLAB FUNDAMENTALS:MATRIX/ARRAY FUNCTIONS THE COLON MATRIX/ARRAY MANIPULATIONINPUT/OUTPUT HP 100 – MATLAB Wednesday, 9/3/2014 www.clarkson.edu/class/honorsmatlab

  2. Before We Begin: • Any Questions? Comments? Concerns? • Feel free to contact Joe or Jim • We can set up small group tutoring or one-on-one • You can email us with any questions or concerns • We are here for you! Even if it isn't about MATLAB

  3. Quote/Video of the Week • “English is ambiguous. If someone said, ‘The horse flies like the devil,’ they could either be advising me on a horse race, or merely commenting on the rising tide of Satanism among some insects.” - Professor Felland Foundations of Mathematics https://www.youtube.com/watch?v=I15bDqhkxwE

  4. Matrix/Array Functions • A = [1 1 1; 1 1 1] • B = [0 0; 0 0; 0 0] • C = [1 1; 1 1] • A = • 1 1 1 • 1 1 1 • B = • 0 0 • 0 0 • 0 0 • C = • 1 1 • 1 1

  5. Matrix/Array Functions • A = ones(2,3) • B = zeros(3,2) • C = ones(2) • A = • 1 1 1 • 1 1 1 • B = • 0 0 • 0 0 • 0 0 • C = • 1 1 • 1 1

  6. Matrix/Array Functions • Built in Commands/Functions: See Tables 3.5,6,7 • max : Maximum Value • min : Minimum Value • mean : Mean Value • median : Median Value • sum : Sum of Vector • prod : Product of Vector

  7. Matrix/Array Functions • Sorting Functions Table 3.8 • sort • sortrows • Size Functions Table 3.9 • size Dimensions of Array • length Largest Dimension

  8. Special Values / Misc. • The following have special meanings: • pi - The constant 3.141592 … • i,j - Imaginary Number • Inf - Infinty, or overflow • NaN - Not a number, Undefined (0/0) • clock - [year month day hour minute seconds] • date

  9. The Colon Operator • Used for: • Creating Vectors • Referencing arrays • Future applications [loops]

  10. Creating Vectors • A = [2 4 6 8 10 12] • B = [2:2:12] • C = [4:6:30] • A = • 2 4 6 8 10 12 • B = • 2 4 6 8 10 12 • C = • 4 10 16 22 28

  11. The Colon Operator • Let: • A(2,3) = • A(1, :) = • A(:, 3) = • A(:, 1:2:4) = • A = • 2 9 -3 10 • -4 13 1 6

  12. The Colon Operator • Built-in function – end • A(:,end)= [13; 6; 8] • A(end,end) = 8 • diag(A) = [4; 2; 8] • A = • 4 7 13 • 5 26 • 1 9 8

  13. Matrix/Array Manipulation • You can define new arrays or matrices in terms of other arrays or matrices. • This can be tricky, but always try to say it out loud and visualize what is happening.

  14. I/O – Input / Output • Definition: • Hardcoding: Setting variables equal to particular numbers in the code. • Example: • Calculate the square root of a number. • number = 100; • sqrt_of_number = sqrt(number); • The code snippet always calculates the square root of 100, unless you manually change the code. • What if we want to do it for the number the user chooses (whomever is using your program/code)?

  15. I/O – Input / Output • Methods: • Ask the user for input through the command window. • Load data from files. • Function inputs (We will get to this in a few weeks.) • Input Command: • number = input('Please Specify a Number: ');

  16. I/O – Input / Output • Loading data from files: • Many different ways, depending on what type of file it is. We do this in the future. • Use the load command.

  17. I/O – Input / Output • Calculations, Manipulation, Calculations… • We Still need to display our Results • Methods: • Display in the command window • Good for quick solutions, small amount of data. • Commands: dispfprintf • Write the results to a file. • Great for processing and saving lots of information. • A bit harder to do, can be highly customized. • Commands: fprintfsave

  18. I/O – Input / Output • Command: disp • Example: • x = 5; • disp(x); • disp(['The value of x is ' num2str(x) ‘. Cool Ehh?’]); Converts a number to a string. Tells MATLAB to combine everything inside together into an array, in this case, a character array Things inside of single quotation marks are strings, or just simply text (stored as plain text)

  19. I/O – Input / Output • Command: fprintf • This can be used to either print out to the command window or write to a file. • This is saved for your own reading/learning. • It’s another way to display, also. It allows for more formatting and pretty outputs

  20. Example Code Time • The Golf Ball Example • Please take note of lots of little things that are done, they add to the readability and to the end results being pretty • Problem Description: • Calculate the X-Position and Y-Position of a golf ball hit with an initial speed and angle. Assume constant acceleration from gravity and no drag. Also find the maximum height and display the results.

  21. Homework • Please review/read: • Chapter 3, Chapter 4 • It is very important to review the tables indicated and go through the example problems. • Please do: • 3.4, 4.1, 4.6

  22. Before you go… • Do Problem 4.1 in the book

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