How to import constants / parameters from another file

I have a question about organizing matlab scripts effectively. Here's my current setup:

1. I have a script that defines around 100 constants.
2. A function file needs to access these constants, but passing them as input arguments isn't practical due to the large number of variables.
3. A main script ties everything together: it calls the constants script, the function file, and initializes a Simulink model that also uses these constants. After the simulation, I extract data from the model.

As someone new to MATLAB but with intermediate Python experience, I'm looking for a better way to handle this. In Python, I would use something like

from constants import *

.Is there a recommended approach in matlab for sharing constants across multiple scripts and Simulink models without cluttering the workspace?

Also, Is there any other way to share these constants without using a struct?

Thanks in advance for your help!

[Stephen23]

"A main script ties everything together: it calls the constants script, the function file, and initializes a Simulink model that also uses these constants. After the simulation, I extract data from the model."

Simply call the constants script from within the function file. Solved.

[Muhammad Samin Hasan]

Thanks for the suggestion.

Answer 1

[Ruchika Parag]

Hi @Muhammad Samin Hasan, here are some approaches to handle your setup:

1. Use a MATLAB Class

You can define a class to store your constants. This allows you to encapsulate all your constants in a single entity and access them easily without cluttering the workspace.

classdef Constants
    properties (Constant)
        Constant1 = 10;
        Constant2 = 20;
        % Add more constants here
    end
end

You can then access these constants using Constants.Constant1, Constants.Constant2, etc., in your scripts and functions.

2. Use a Function to Return a Struct

You can also create a function that returns a struct containing all your constants.

function c = getConstants()
    c.Constant1 = 10;
    c.Constant2 = 20;
    % Add more constants here
end

3. Use a MATLAB Script with load and .mat Files

Another option is to save your constants in a .mat file and load them when needed. This can be useful for Simulink models as well:

1. Create a script that saves your constants to a .mat file:

Constant1 = 10;
Constant2 = 20;
% Save all constants
save('constants.mat', 'Constant1', 'Constant2');

2. Load these constants in your script or function when needed:

load('constants.mat');

4. Simulink Parameter Objects

For Simulink models, you can use MATLAB's 'Simulink.Parameter' objects to define and manage constants. Please refer to the following official MathWorks documentation to know more:https://www.mathworks.com/help/simulink/slref/simulink.parameter.html

Using a class or a function to return a struct is often the most straightforward approach for sharing constants across scripts and functions without cluttering the workspace. For Simulink integration, consider using Simulink.Parameter objects or .mat files. Happy coding!

Answer 2

[Yash]

Hi @Muhammad Samin Hasan

To efficiently manage constants in MATLAB, you can define them within a MATLAB class and create an instance of this class in your main script. Below is an example of how you can implement this:

constants.m

classdef constants
    properties (Constant)
        a=1;
        b=2;
        c=3;
        d=4;
    end
end

main.m

consts = constants;
totalVal = consts.a + consts.b + consts.c + consts.d;

For more detailed information on user-defined classes, refer to the following documentation: https://www.mathworks.com/help/matlab/matlab_oop/user-defined-classes.html

While you could also use MAT files or execute M files directly with the "run" function, these methods might clutter your workspace. Therefore, using a class to encapsulate your constants is a cleaner and more efficient solution.

I hope you find this helpful!

[Muhammad Samin Hasan]

Thanks for the suggestion.