Workspace, Variables, and Functions in MATLAB

Workspace

• The workspace contains all variables we create while working in MATLAB.
• Whenever we assign a value to a variable, it automatically gets space in the workspace.
• Workspace variables lose their existence after the closing of the environment, so save these variables in a file to use later on.
• We can import variables into MATLAB from data files.
• We can import variables into MATLAB from other programs also.
• The assignment operator (=) facilitates the creation of variables.
• To access the variable from the workspace, we need to enter its name at the command line.
• To view all available variables in the workspace, enter the command- 'whos' at the command line.

Workspace Pane in MATLAB

• It is an area in the MATLAB environment with the name Workspace written on its top bar.
• All variables currently being used or in the workspace, are displayed here.
• Workspace pane can be maximized or minimized as per requirement.
• We can add or remove the fields of the contents, which describe variables.

MAT-file in MATLAB

• The file saved with .mat extension is called a MAT-file in MATLAB.
• As variables in the workspace no longer exist after the closing of the environment, so these variables are saved in MAT-file for later use.
• Use save command to save workspace contents in a file.
• Ensure the file name is different from the previous file. Otherwise, it will overwrite the last existing file with the new one.
• It saves the current workspace in the current working folder and a compressed file.

Current Folder Pane

• We can change the current working folder by using the Browse For Folder button located above the current folder pane.
• After running the save command, the file saved with .mat extension becomes visible in the Current Folder Pane.
• After saving the workspace, we can clear all the contents of the workspace by using the clear command at the command line.
• Syntax of the save command:

Using .mat files

• Any .mat file can be included in the current workspace.
• Use command load followed by filename with extension.
• Syntax:

• Before loading the file, ensure the parent folder is selected as the current folder; otherwise, it will show error:

Workspace after saving the file, clearing the content of the workspace, and before loading of the file:

Workspace after loading of the file, now we can use variables inside that file:

Text and Characters in MATLAB

Text in String Arrays

• When text is enclosed in double quotes (" "), its data type or class is declared as String.
• Strings are also arrays, like all other MATLAB variables.
• Syntax:

Double quotes inside double quotes

• When the text of the String itself includes double quotes, then use double quotes within the text, as:

Using whos command to View a single variable

• As 'whos' command shows all variables within the workspace, we can use 'whos variable_name' command to view only the particular variable.

Concatenation of String using plus (+) operator

• We can combine the value of other variables into a String.

Find the length of the String array in MATLAB

• We can find the length of a string by using the strlength function.

String array with multiple elements

• String array can also have multiple elements like number arrays.

Find the length of String array with multiple elements

• The same strlength function is used to find the length.
• It will display length in an array format with length calculated as an individual element.

Character Arrays in MATLAB

• We use character array to store data that is not meaningful, or we can say that it doesn't resemble a text, such as a key or a password sequence, a DNA sequence.
• Character array has a char data type.
• Character array is declared in single quotes (' ').

Find a single character in character array

• In character array, each character is stored as a separate element.
• To find the character of an element, use the index number of that element in parenthesis with the variable.

Concatenation of Character Array in MATLAB

• As we concatenate numeric arrays, here also use square brackets to concatenate character arrays.

Calling Functions in MATLAB

• In MATLAB, a large number of functions are available that perform computational tasks.
• These functions are the same as subroutines or methods in other programming languages.
• Functions are called providing input arguments in its parenthesis.
• Example:
  • function-name....max()
  • use.....finds the largest value in the array.

• If it is a matrix, it will find the maximum value column-wise.

• Use a comma to separate multiple input arguments.
• Passing multiple arguments requires to agree on the matrix dimensions, as per calculation.

disp function in MATLAB

• Used to display the input data as it is.
• It doesn't store the output to the default ans variable.
• Inputs for the function are provided in parenthesis.

clc function in MATLAB

• It clears the command window by erasing all commands and outputs.
• But previously entered commands can be accessed by using keyboard array keys on the command line.
• It doesn't take any input, so it doesn't output anything.