Leanne Kuwahara-Week 10

Purpose

To learn how to use matlab and create files MyFirstScript, LetsLoop and PlotTime.

'clc' to clear screen
matlab returns 'ans = 1' when no variable is entered
create own variable: 'myvar = x'
- ';' suppresses output
- types of variables:
  - scalar = x
  - vector = [x y z]
  - column vector = [x; y; z]
  - matrix = [x y z; a b c; q r s]
  - to extract from matrix:
    - matrix(row, col)
  - for whole row/col:
    - matrix(row,:)
  - for subset of matrix:
    - matrix(row,1:2)
- variables shown in work-space
  - clear from work-space 'clear myvar' (or 'all' if want all variables to delete)
can see command history 'layout >> command history'
- double click command to run again
- click and drag to edit
can format 'long' or 'short' to change number of decimal places shown
types of variable classes:
- double
- single
- Boolean (logical): T/F
cell array: similar to a matrix, but can include multiple data types
- mycell = {[1 2 3] [4 5 6 7]; 'v1' 'v2'}
  - row 1: vector of doubles
- row 2L vector of strings
  - access similar to matrix, but with '{}'

script: series of text files the matlab runs sequentially
comment: '%'
- can highlight, right click, 'comment' to comment out a large chunk of text
send text ot command line: 'disp('string')'
random integers: 'randi(row,col)'
transpose: swap rows and cols in matrix
- Transpose = MatrixVar'
  - hit 'run' to get commands to appear in window
make matrices of all zeros/ones
- myZeros = zeros/ones(rows,cols)
can right click on functions for help/explanation
matrix multiplication/div vs. element multiplication/div
- matrix multiplication/div: M1*M2
- element multiplication/div: M1.*M2
If statements
= input(‘please enter a number: ’)—for keyboard input
- if: first condition
  - disp(“negative”)
- elseif second condition
  - disp(“perfect”)
- else—"catch all”
  - disp(“too big”)
- end
switch statements: to implement patterns, or “clean-up” if statements
- get two input values (n, m) and type of calculation
- switch action
  - case ‘add’
    - output = n + m
  - case ‘subtract’
    - output = n-m
  - otherwise
    - disp(“sorry, no can do.”)
  - end
for loops
- need to set up index as vector
  - for i = 1:10
    - disp(i)
  - end
- to move in steps of 2: for i = 1:2:10
  - can set step size and end number before hand as variables
While loop: continues to run when while a certain flag is true, once flag is false, while loop stops
- be careful of infinite loops
- good to test threshold values
  - set threshold variable
- ’break’ exits threshold

make sure function is in the matlab path
use = csvread(‘fliename.csv’); to import external data
can “debug” or check script at breakpoints (dashes near numbers)
’tictoc’ function tells how long it takes to run a function
- can pre-allocate time when working with large datasets

making plots
plot(data)
can turn on grid (‘grid on’)
can adjust axis
- ’axis tight’
- ylim([min,max])
can change color (y, m, c, b) of plot and type of marker by using a ‘string’ command after data
can add annotations to plot
- xlabel(‘x-axis’)
- ylabel(‘y-axis’)
- title(‘title’)
- legend(‘legend1’,legend2’)
can input images
- myIm = imread(‘filename.jpg’)
can plot in 3D
- use surf function
- can add color bar (‘colorbar’) showing max and min values
  - be careful of punctuation marks, spaces, and capitalizations!!!

Except for what is noted above, this individual journal entry was completed by me and not copied from another source.

Dahlquist, K. & Fitpatrick, B. (2019). "BIOL388/S19: Week 10" Biomathematical Modeling, Loyola Marymount University. Accessed from:Week 10 Assignment Page
Moser, S. (2018). Learning MATLAB. 'Lynda Learning:Linkedin.' Accessed From: https://www.lynda.com/MATLAB-tutorials/Learning-MATLAB/688521-2.html