In this article, you’ll learn the basics of MATLAB Programming in 5 minutes, including how to:

  • Create variables, vectors, and matrices
  • Use MATLAB functions and scripts
  • Create loops and conditions
  • Read and write text and Excel files

Creating Variables, Vectors, and Matrices

How to Define a Variable in MATLAB

To define a variable, write the name of the variable followed by “=” and the value of the variable:

numberVariable = 5; % variable containing a number
stringVariable = 'string'; % variable containing a string
  • The “;” is used to prevent MATLAB from displaying the value of your variable in your workspace when you define it.
  • The “%” is used to add a comment to your code.

Furthermore, MATLAB remembers what you wrote. If you want to access a command that you wrote earlier in your workspace, use the up arrow key to get your previous command.

How to Create a Vector in MATLAB

In MATLAB, you can create row vectors and column vectors:

  • Row vector: create a vector in MATLAB by putting numbers (or strings) next to each other and enclosing them with square brackets: 
    vector = [1 2 3 4 5]; % row vector
stringVector = [{'speed'} {'size'}]; % string row vector

    This defines the following vectors:

    \(vector=\begin{pmatrix}1 &2 &3&4 &5\end{pmatrix}~~~~~~~~~~~~~~~~~~stringVector=\begin{pmatrix}\{‘speed’\}& \{‘size’\}\end{pmatrix}\)

  • Column vector: use a single quotation mark to define a column vector: 
    vector = [1 2 3 4 5]'; % column vector
stringVector = [{'speed'} {'size'}]'; % string column vector

    \(vector=\begin{pmatrix}1 \\2 \\3\\4 \\5\end{pmatrix}~~~~~~~~~~~~~~~~~~stringVector=\begin{pmatrix}\{‘speed’\}\\\{‘size’\}\end{pmatrix}\)

    As you can see, you need to use braces to separate strings in a vector; otherwise, MATLAB tries to concatenate them.

If you want to learn all the technical stuff on vectors, see MATLAB Vector Tutorial: Create, Add, Concatenate, and Extract

How to Create a Matrix in MATLAB

You can create a matrix in MATLAB by writing numbers or strings next to each other to define the rows and using a semicolon to go to the next row:

 matrix = [1 2 3 ; 4 5 6 ; 7 8 9];
 stringMatrix = [{'position'} {'speed'} ; {'size'} {'acceleration'}];

The result is the following matrices:

\(matrix=\begin{pmatrix}1 &2 &3\\4 &5 &6 \\7 &8 &9\end{pmatrix}~~~~~~~~~~~~~~~~~~stringMatrix=\begin{pmatrix}\{‘position’\}& \{‘speed’\}\\\{‘size’\} & \{‘acceleration’\}\end{pmatrix}\)

You can then multiply matrices as the following:

 A*B % classic matrix multiplication in MATLAB

If you want to learn more about matrices, see MATLAB Matrix: Create, Transpose, Extract, Multiply Matrices

MATLAB: Function and Script

Writing a Script

To write a new MATLAB script, follow these steps:

  1. Go to the top left of your MATLAB windows, under the “HOME” tab
  2. Click on “New Script“:
    define a MATLAB function by clicking on New Script
  3. Save your script by using the keyword shortcut “CTRL+S” or by clicking “Save” at the top left of the MATLAB editor:
    Save a MATLAB script using the Editor

Defining a MATLAB Function

Here’s the syntax to define a MATLAB function:

function [out1, out2, out3] = functionName(in1, in2)
 
Instructions
 
end
  • Outputs: list every output of your function separated with commas in between square brackets.
  • Inputs: list input separated by commas and enclosed by parenthesis.

If you want to know all the nitty-gritty details of MATLAB functions, see MATLAB Function: Vector, Matrix, Or Single Input/Output Functions.

Creating Loops and Conditions

MATLAB for Loop

You can define a for loop in MATLAB as the following:

for i = 1:n % n is the number of loops you want
    Instructions; % what you want to do n times
end

For example, here’s how to create a for loop that counts to 10:

for i = 1:10
    i
end

To see more examples of for loops, see MATLAB For Loop: Example of Simple, Backward, and Nested For Loops.

While Loop

If you want to define the while loop in MATLAB, you can use the following syntax:

while condition 
      Instructions
end

For example, here’s how to create a wide loop that counts to 10:

i = 10;
while i~=10 % while i is not equal to 10
      i=i+1
end

If Else MATLAB

The basic if else MATLAB structure is:

if firstCondition
      firstInstruction
elseif secondCondition
      secondInstruction
else
      otherInstructions
end

For example, if your condition is “A is not equal to B,” you’d have:

  • A and B matrices: 
    if ~isequal(A, B)
          instruction
end
  • A and B numbers: 
    if A~=B
          instruction
end

If you want to learn more complicated examples such as switch case structures, A less than or equal to B, or strings and logical operators, see If Else MATLAB: Conditional Statements if A Is Not Equal to B.

MATLAB: Reading and Writing Files

Text Files

  • To read a text file, you need to open it with the fopen MATLAB command, read it using a while loop, and close it using the fclose MATLAB command:

    fid = fopen(fileName);
while ~feof(fid)
      textLineEntry = fgetl(fid);
end 
fclose(fid);

    To learn more about how to read a text file in MATLAB, see  MATLAB: Read a Text File Line By Line Using fgetl.

  • Using the same structure, we can employ the fprintf MATLAB command to write a new text file. For example, here’s how to write the word “Text” in a new text file named “textFileName.txt”:

    fid = fopen('textFileName.txt', 'at');
fprintf(fid, 'Text');
fclose(fid);

    To learn more about the fprintf MATLAB command, see fprintf in MATLAB: Text, Matrix, and Complex Number.

Excel Files

  • Reading an Excel file: an easy way to read an Excel file is to use the xlsread MATLAB command. Here’s the basic syntax for that command:

    [numbers text textAndNumbers] = xlsread(excelFileName, sheetNumber);

    If you want more explanations and examples of how to use this function, see Xlsread Tutorial: Extract Data from Excel in MATLAB.

  • Writing into an Excel file: to write into an Excel file, use the following:

    xlswrite(fileName, data, sheetNumber);

    For example, if you want to write the following matrix into an Excel file:

    \(\begin{pmatrix} \{‘firstWord’\}&\{‘secondWord’\}\\\{‘thirdWord’\} &\{‘fouthWord’\} \end{pmatrix}\)

    You can do the following:

    variable1 = 'firstWord';
variable2 = 'secondWord';
variable3 = 'thirdWord';
variable4 = 'fourthWord';
data = [{variable1} {variable2} ; {variable3} {variable4}];
fileName = 'excelFile.xlsx';
sheetNumber = 1;
xlswrite(fileName, data, sheetNumber);

Jacob Sapir
Jacob Sapir