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.

Answer 1

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!