matlab - RicoJia/notes GitHub Wiki

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1. Cell

   • a cell is similar to a matrix, but can contain any datatype. cell{1} constructs a cell with value 1.

2. function organization: foo can only be used in getScore, but not outside the file.

   1. funcs.m: 
   function g = getScore(input)
       g = foo(1)
   end
   
   function f = foo(input2)
       f = input2+1  
   end
   

3. class organization:

   • Definition

     classdef My_Class
         properties  #(GetAccess='private', SetAccess='private', Constant)
             h
         end
         methods
             function obj = My_Class(input)      %%constructor
                 obj.h = 3
             end     
             function g = getScore(input)
                 g = foo(1)          %% definition of the func here
             end
         end
         methods (static)            %% static helper functions
             function g = staticMethod()
                 print lol
             end
         end
     end 
     
     function f = foo(input)
         f = f + 1
     end 

   • And in commandline window, you can set properties:

     s=My_Calss(input)   %% or simply s = My_Class if no inputs are required. 
     s.h = 123

   • use static methods without creating an object: My_Class.staticMethod()

   • handle class: inherit is <, matlab has built-in handle class that allows you to build a class that's used as a reference. So if your class is a big data structure, make it a handle class so functions do need to return it!! This can also be used in multiple workspaces.

   • events: like subscribers, it will trigger a callback.

   • func(@evCallback) %% you're passing a function in.

4. By default, classes have value behavior.

5. Set Path of the currrent directory.

   • Online MATLAB should use pathtool to add path. Then, add_with_subfolders.

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1. How to run program: step, or run

2. ginput() gives you a set of points from screen

3. matrix

   • a = [1, 2, 3; 4, 5, 6]
   • mat(1,1): how you access it, starting from 1
   • appending a new element: arr(1) = 3
   • last element: arr(some_index)
   • [mat1; mat2; mat3] is how we stack them

4. polyval evaluate a polynomial (Pnxn^{n<\sup> + ...) decending powers polyval([], num)}

   flipud(list): reverse it

5. function definitions are behind the script

6. help zeros: help

7. indentation in matlab doesn't matter

8. clc clean screen

9. ; suppress command line inputs

10. nested func: all variables are the same here

    function foo()
      x = 100; 
      function bar()
        x = 99;
      end
    end

11. function return, must be like function [var] = something()

12. if -else -elif

    if 
    else 
    elseif 
    end

13. nargin: number of arguments

1. ^ is matrix power, .^ is element power
2. isempty for checking arrays
3. rem(a,b) for checking remainders
4. nchoosek(n, k),c_n^k
5. addpath ../ to add another dir
6. length(arr): length of the array,
   • similar to size(arr, ndim)
7. rand: uniform (0, 1)
8. pi
9. x(x<0)=0 if x<0, x=...
10. Mat can be flattened out into 1d

    M = [1,2
         3,4]
    M(1) = 1 
    M(2) = 3

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1. matlab no tiene +=
2. Definir variables globales es difficil, atraves de los archivos
3. arr(1:2) = [1;2] es valido