Matlab lecture 3.5

Signed-off-by: Aaron Erhardt <aaron.erhardt@t-online.de>

Matlab/Matlab.md

@@ -134,16 +134,17 @@ Histogram
 
 ```matlab
 histogram(A)
+histogram(A, 15) % place values in 15 groups
 ```
 
 ## Images
 
-Load image
+### Load image
 
 ```matlab
 img = imread('path_to_file')
 ```
-
+### 
 Show image
 
 ```matlab
@@ -159,14 +160,14 @@ colormap(M)      % where M 255x3 with values from 0 to 1
 
 ## Strings
 
-Create
+### Create
 
 ```matlab
 str = "Hello"
 fromChar = string(text)
 ```
 
-Concatenate
+### Concatenate
 
 ```matlab
 str2 = str + " World!"
@@ -174,28 +175,26 @@ str2 = str + " World!"
 
 ## Character array
 
-Create
+### Create
 
 ```matlab
 text = 'Hello'
 fromStr = char(str)
 ```
 
-Concatenate
+### Concatenate
 
 ```matlab
 text2 = [text ' World!']
 ```
 
-Access characters
+### Access characters
 
 ```matlab
 c = text(1) % first character
 ```
 
-### Convert
-
-string to number
+### Convert to number
 
 ```matlab
 str2num('2')
@@ -203,19 +202,19 @@ str2num('2')
 
 ## Output
 
-Create formatted string
+### Create formatted string
 
 ```matlab
 sprintf('value: %f', float_val)
 ```
 
-Print string
+### Print string
 
 ```matlab
 disp('Hello')
 ```
 
-Print formatted string
+### Print formatted string
 
 ```matlab
 % use \n for newline, the 1 is for printing to stdout
@@ -225,9 +224,7 @@ fprintf(1, 'value: %d\n', 2)
 
 # Datatypes
 
-## Structs
-
-Create struct, add fields and access fields
+## Struct
 
 ```matlab
 student.name = "TestStudent"                     % create
@@ -240,19 +237,19 @@ disp(student.name)                               % print name
 
 Array containing different data types
 
-Create
+### Create
 
 ```matlab
 ca = { 'chars', 9.81, 1 } % 1x3 cell array
 ```
 
-Access elements
+### Access elements
 
 ```matlab
 ca(1) % -> 'chars'
 ```
 
-Length
+### Get length
 
 ```matlab
 length(ca)
@@ -260,26 +257,26 @@ length(ca)
 
 ## Table
 
-Properties
+### Properties
 
 ```matlab
 table.Properties
 table.Properties.VariableNames{1} % first column name
 ```
 
-Access column by name
+### Access column by name
 
 ```matlab
 table.column_name % access column (as vector) with name "column_name"
 ```
 
-Get sub-table
+### Get sub-table
 
 ```matlab
 table(:, 2) % second column as table
 ```
 
-Access values
+### Access values
 
 ```matlab
 table{1, 2} % row 1, column 2, note brackets!
@@ -291,8 +288,6 @@ table{:, 2} % column 2
 
 ## Workspace
 
-Save and load
-
 ```matlab
 save file_name
 load file_name
@@ -300,8 +295,6 @@ load file_name
 
 ## Table
 
-Load
-
 ```matlab
 table = readtable('file_name')
 detectImportOptions('file_name') % return detected import options
@@ -313,7 +306,6 @@ detectImportOptions('file_name') % return detected import options
 matrix = readmatrix('file_name') % like readtable but only values as matrix
 ```
 
-
 ## File
 
 ```matlab
@@ -321,6 +313,7 @@ file_handle =  fopen('file_name', 'rw') % open as readable and writable
 fclose(file_handle)
 ```
 
+
 # Polynomials
 
 ## Fit polynomial to points
@@ -377,6 +370,13 @@ semilogx(x, y); % x-axes is logarithmic, y-axis is linear
 semilogy(x, y); % x-axes is linear, y-axis is logarithmic
 ```
 
+### Simple function plot
+
+```matlab
+fplot(@sin);           % default, from -5 to 5
+fplot(@sin, [-pi pi]); % from -pi to pi
+```
+
 ## Charts
 
 ### Bar
@@ -520,6 +520,110 @@ handle.Children(1).LineWidth = 2; % get line from handle and change width
 ```
 
 
+# Functions
+
+## Regular functions
+
+### Definition
+
+```matlab
+% global function, always at the top of a file
+function file_name()
+    % code...
+end
+
+% local function
+function FuncName()
+    % code...
+end
+```
+
+### Parameters
+
+```matlab
+function funcName(param1, param2)
+    disp(param1); % print param1
+    disp(param2); % print param2
+end
+```
+
+Variable parameters
+
+```matlab
+function funcName(param1, param2, varargin)
+% function takes at least two parameters
+    
+    for cnt = 1:length(varargin)
+        arg = varargin{cnt}; % get one of the variable arguments
+        if isnumeric(arg)    % only print numeric values
+            disp(arg);       % print variable parameters
+        else                 % ignore non-numeric values
+            disp("Can't display non-numeric values");
+        end
+    end
+end
+```
+
+### Return values
+
+```matlab
+function returnValue = duplicate(param)
+    returnValue = [param param];
+end
+
+value = duplicate(2) % value = [2 2]
+
+% multiple return values
+function [returnValue1, returnValue2] = funcName(param1, param2)
+    returnValue1 = param1;
+    returnValue2 = param2;
+end
+
+[value1, value2] = funcName(2, 3) % value1 = 2, value2 = 3
+```
+
+### Documentation
+
+```matlab
+function funcName()
+% This is a documentation comment
+% Explain what your function does here
+
+% This is a normal comment again
+end
+```
+
+## Anonymous functions
+
+### Get function handle
+
+```matlab
+handle = @sin
+handle(1) % returns sin(1)
+```
+
+### Define anonymous function
+
+```matlab
+handle = @(param) 2 * cos(param * 2) % handle(1) returns 2*cos(2)
+handle = @(x) exp(x-x.^2) - 0.5
+```
+
+## Function characteristics
+
+### Zeros
+
+```matlab
+fzero(handle, 1) % find a zero value starting from 1
+```
+
+### Fit parameters
+
+```matlab
+id = @(is,ud)is*exp(ud/0.05)  % diode current
+is = lsqcurvefit(id, 1e-10, u, i); % find ideal value for is to fit measured values u and i
+```
+
 # Control structures
 
 ## for-loop
@@ -584,6 +688,7 @@ switch value
 end
 ```
 
+
 # Performance
 
 ## Time measurment