📚 M SCRIPTING

💡 What is M-Scripting (MATLAB Scripting)?

M-scripting refers to writing code in MATLAB using .m files, which include scripts and functions. It allows for: - Data processing - Algorithm development - Simulation automation - Plotting & visualization - Model control (e.g., running Simulink models via script)

📍 Where is it used?

Controlling Simulink model simulations
Automating test cases (MIL/SIL)
Post-processing results (e.g., signal logs, plots)
Writing reusable utility functions
Performing batch regression tests
Creating configuration scripts for automotive domains

📅 When do we use it?

During model development
For automated testing pipelines
To generate and document results
When building toolchains for code generation, verification

❓ Why use M-scripts?

Automation: Run tasks, load data, execute models without GUI
Customization: Build test frameworks and utilities
Reusability: Define functions for common engineering operations
Efficiency: Avoid repetitive manual actions

⚙️ How do we use it?

Create .m files with code and logic
Use control structures (if, for, while)
Interface with Simulink models using set_param, sim, get_param
Perform data handling using tables, matrices, cell arrays, structs
Integrate with toolboxes or use for test automation

🌟 Benefits

✅ Simplifies repetitive tasks
✅ Helps in building test frameworks
✅ Makes simulation runs reproducible
✅ Enables clean and structured development
✅ Easy to integrate with CI/CD and test tools like Jenkins or JIRA
✅ Great for logging, visualization, post-analysis

🧩 Basic MATLAB Scripting Commands & Their Use

Command	Use
`clc`	Clears the Command Window
`clear`	Removes variables from workspace
`close all`	Closes all open figure windows
`disp(x)`	Displays value of `x`
`fprintf()`	Prints formatted data to screen or file
`load('file.mat')`	Loads variables from a `.mat` file
`save('file.mat')`	Saves variables to a `.mat` file
`plot(x, y)`	Plots x vs y
`title('text')`	Adds title to plot
`xlabel('x')`, `ylabel('y')`	Labels x and y axes
`legend()`	Adds legend to plot
`hold on`	Allows multiple plots on same axes
`axis([xmin xmax ymin ymax])`	Sets axis limits
`if`, `else`, `elseif`, `end`	Conditional statements
`for i = 1:N`	Looping from 1 to N
`while condition`	Loop while condition is true
`break`	Exit loop early
`continue`	Skip current iteration
`function out = name(in)`	Function definition
`sim('modelName')`	Runs a Simulink model
`set_param()`	Set block/model parameter
`get_param()`	Get block/model parameter
`exist('var', 'var')`	Check if variable exists
`isnan(x)`	Check if value is NaN
`size(x)`	Returns dimensions of array `x`
`length(x)`	Returns largest dimension of `x`
`zeros(n,m)`, `ones(n,m)`	Create n-by-m array of 0s or 1s
`rand(n)`	Generate n-by-n random matrix
`linspace(a,b,n)`	Generate `n` points between `a` and `b`
`mean(x)`	Compute mean of x
`std(x)`	Compute standard deviation
`max(x)`, `min(x)`	Find max/min values
`sum(x)`, `prod(x)`	Sum/product of array elements
`input('msg')`	Get input from user
`pause(n)`	Pause execution for n seconds
`try...catch`	Error handling block
`gca`, `gcf`	Current axes, current figure handles
`eval('code')`	Execute string as MATLAB code
`cd`, `pwd`, `ls`	Directory navigation
`who`, `whos`	List variables in workspace

MATLAB M-Scripting Interview Q&A

1. What is an M-script in MATLAB?
A script written in a .m file that contains a sequence of MATLAB commands.

2. How is an M-script different from a function?
Scripts don’t take inputs or return outputs; functions do.

3. How do you create an M-script?
Create a new .m file and save it with your code.

4. What command is used to run an M-script?
Just type the file name (without .m) in the command window.

5. What is the command to run a Simulink model from a script?
sim('modelName')

6. How do you automate test cases using scripts?
By looping through test inputs and calling Simulink models with sim().

7. What function is used to set parameters in a Simulink model?
set_param()

8. What is get_param() used for?
To retrieve model, block, or signal parameters.

9. How do you store simulation output in a script?
By capturing the output of sim() like:

out = sim('modelName');

10. What function is used to create plots?
plot(x, y)

11. How can you use conditions in scripts?
Using if, elseif, and else.

12. How do you loop in MATLAB?
Using for and while loops.

13. How do you suppress output in MATLAB?
Add a semicolon ; at the end of the statement.

14. What is the use of disp()?
To display text or variable values.

15. How can you create a function inside an M-script?
Add a function block at the end of the script (in recent MATLAB versions).

16. How do you handle errors in scripts?
Use try and catch blocks.

17. What is the use of exist()?
To check if a variable or file exists.

18. How do you load .mat files in scripts?
Using load('filename.mat').

19. What does clear do?
Clears variables from the workspace.

20. What does clc do?
Clears the command window.

21. How to save simulation outputs from scripts?
Use save('filename.mat', 'variableName')

22. How do you write data to a text file?
Using fopen, fprintf, and fclose.

23. What is the fprintf function for?
Formatted data printing to the screen or file.

24. How do you generate test input signals in a script?
Use functions like sin, linspace, rand, or custom arrays.

25. What are common uses of M-scripts in automotive?
MIL testing, batch simulations, test automation, plotting results.

26. What does pause do?
Temporarily stops script execution.

27. How do you call a function from a script?
Just type the function name and pass inputs.

28. How do you debug an M-script?
Use breakpoints and the dbstop, dbstep, dbclear commands.

29. How do you use global variables in scripts?
Use the global keyword.

30. What is the difference between length() and size()?
length() returns the largest dimension, size() returns both.

31. How do you vectorize operations in MATLAB?
Use array/matrix operations instead of loops.

32. How do you check for NaN in a script?
Use isnan().

33. How do you define a cell array?
C = {1, 'text', [1 2 3]};

34. What is the benefit of scripting for testing?
Automates tests, repeatability, saves time, traceability.

35. How do you execute a script from another script?
Just call the filename without .m.

36. How do you generate plots for multiple datasets?
Use hold on and multiple plot() calls.

37. How do you add titles and labels to plots?
Use title(), xlabel(), ylabel().

38. What does gca and gcf stand for?
Current axes and current figure handles.

39. How do you loop through signal names in a list?
Use a for loop with cell arrays.

40. How do you compare expected vs actual values?
Use assert() or difference-based checks with tolerance.

41. What’s the role of simOut.logsout?
Access logged signals from Simulink.

42. How do you log signals in a script?
Enable logging in Simulink, access via simOut.

43. Can you run a script from a button in Simulink?
Yes, using a callback that triggers evalin('base', 'scriptName').

44. What is eval() used for?
Executes a string as a MATLAB command.

45. What is the use of input() in scripts?
Takes user input during script execution.

46. What is switch-case used for?
Alternative to if-else for handling multiple conditions.

47. What does who and whos show?
Lists all variables and their details.

48. How do you define an inline anonymous function?

f = @(x) x^2;

49. What is cellfun or arrayfun used for?
Apply a function to each cell/array element.

50. Why is M-scripting important in automotive MBD?
Helps automate modeling, testing, simulation, data processing, and reporting — making engineering efficient and traceable.