MATLAB function syntax within script?

Question

Having some trouble declaring functions within my script:

%Read the raw audio data

refData = wavread('file1.wav');
userData = wavread('file2.wav'); 

% I want to continue writing my "main" function here, and call the below functions

%%%%%%%%%%%%%
% Functions %
%%%%%%%%%%%%%

%Vector x
function preEmphasis(x)
    alpha = 0.95;
    len = length(x);
    for i=1:len
        x_i = x(i);
        x_iMinus1 = x(i-1);
        x(i) = x_i - alpha*x_iMinus1;
    end
end

%Vector x
function normalization(x)
    maxVal = max(abs(x));
    x = x / maxVal;
end

%Vector x; numFrames, frameSize: integers; stepSize: percentage (float, 0.2 -> 0.5 for example)
function Ymatrix = createYmatrix(x, numFrames, frameSize, stepSize)
        Ymatrix = zeros(numFrames, frameSize);
        for i=1:numFrames
            for j=1:frameSize
                Ymatrix(i,j) = x(stepSize*i + j);
            end
        end
end

The words "function" and "end" are highlighted in red as "parse errors". How can I fix this? Thanks.

Eitan T · Accepted Answer · 2013-01-16 23:36:18Z

6

You can't declare functions within your main script. You have to create an external m-file and implement your function inside it, like it says in the official documentation:

Any function that is not anonymous must be defined within a file.

(just to be clear, a script does not accept input arguments or return output arguments).

However, you can have local functions declared inside a function m-file. Read more about function declarations in the official documentation.

EDIT: You can Refer to @natan's answer if you're looking for a way to avoid function m-files altogether. He implemented your functions as anonymous functions, which can be declared inside the script file. Good luck!

edited Jan 16, 2013 at 23:36

answered Jan 16, 2013 at 19:32

Eitan T

33k14 gold badges77 silver badges111 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

JDS Over a year ago

"Local functions inside an m-file" Isn't that what I'm trying to do here? At least that's what I would want... tired of this multiple file nonsense for quick scripting lol.

Eitan T Over a year ago

I believe not. I think it's your main script, since it doesn't have a function declaration in its the beginning.

JDS Over a year ago

But otherwise what I'm doing with function ... end is correct and I can just move all the functions into another file?

Eitan T Over a year ago

The end is optional in the case of your function. Just create an m-file named "mymainfunc.m", that starts with for example: function y = mymainfunc(x), implement it and copy paste the rest of your functions inside it. Then call mymainfunc from your main script. Note: your m-file must be called like the main function in that file. Also, this question might also clear things up...

Eitan T Over a year ago

If you want "quick" scripting, you can always make a function run in a run.m file, and implement everything inside it. You'd still have to make a main script and invoke run, though... OR just try to manage without functions :)

|

bla · Accepted Answer · 2013-01-16 21:55:12Z

1

In Addition to what Eitan mentioned, here is how to implement an anonymous functions in your case, note that code vectorization is a must. For example, in your case instead of normalization you can write:

normalization = @(x) x./max(abs(x));

and then use it as if it was a function, y=normalization(x)

For preEmphasis:

preEmphasis= @(x) [x(1) x(2:end)-0.95*x(1:end-1)];

Your current code has a bug for the case i=1 so I interpret that as for=2:len instead;

The solution for Ymatrix is a bit ugly (haven't invested to much time vectorizing it nicely), but it should work:

Ymatrix = @(x, numFrames, frameSize, stepSize) ...
          ones(1,numFrames)'*x(1+stepSize:stepSize+frameSize)+...
          meshgrid(0:stepSize:stepSize*numFrames-1,ones(1,frameSize))';

edited Jan 16, 2013 at 21:55

answered Jan 16, 2013 at 20:17

bla

26.1k11 gold badges72 silver badges105 bronze badges

2 Comments

Eitan T Over a year ago

LOL, I've just suggested it in one of my comments :) +1 anyway. I wonder if createYmatrix can be made into an anonymous function :P

bla Over a year ago

yes Ymatrix can be made to an anonymous function, see my edit

Andrew Janke · Accepted Answer · 2013-01-17 02:42:22Z

1

Just turn your script into a function; then you can use local and nested functions. Use return values or assignin if you need to get values back in to the base or caller's workspace.

answered Jan 17, 2013 at 2:42

Andrew Janke

24k5 gold badges60 silver badges89 bronze badges

Collectives™ on Stack Overflow

MATLAB function syntax within script?

3 Answers 3

6 Comments

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

6 Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related