Undefined function 'times' for input arguments of type 'cell'

I'm performing the lme model with longitudinal data analyzed using free surfer, I have created this matrix:

X = [ones(length(M),1) M M(:,1).*M(:,2)];

but I have the following error

Undefined function 'times' for input arguments of type 'cell'.

What is it wrong? enrica

[Oleg Komarov]

M is a cell array and multiplication is not defined for cell arrays.

Answer 1

[Iain]

When you want to access the contents of "M", you need to access it like this:

 M{:,1}

[enrica]

Thanks Lain! when I tried to do this: X = [ones(length(M),1) M M{:,1}.*M{:,2}]; the error is Error using .* Too many input arguments.

any other tips?

[Iain]

It really depends what the contents actually are and exactly what you want out of it...

You may need to do this:

 [M{:,1}]

You may need to do this:

 reshape([M{:,1}],[],1)

You may need to change the result into a cell array, you may need to change the "ones" into a cell array..

[enrica]

I would like to create a matrix X where the first column is the column of 1s (the intercept), the 2nd column the time covariate (took from the column 1 of matrix M), 3rd column with the group (took from the column 2 of matrix M) and the interaction term of two previous variables (time*group) M{:,1}.*M{:,2} Sorry, but this is my first time with matlab.

[Iain]

There's no need for you to apologise. :)

Try the code, look at the answer, decide for yourself if it's working. If it's working, great. If it's not, and you can't figure out how to put it right, ask another question.

Answer 2

[g.shaanti]

Hello, I realize this is an older post, but I would like to put another possibility out there for what can be wrong (and a solution):

This is for if you've ensured that the function you're trying to call both exists and is definitely on your path, but MatLab is still throwing this error (as was the case for me).

The folder containing the function I was trying to run was labelled with slightly unusual characters (so that it would appear at the top of the directory where I needed it).

Folder title: "--> title of folder" (the quotes are not part of the folder title)

I finally got the function to run when I moved it into a folder outside of "--> title...", and it ran without a problem. I have a feeling the "-->" characters in the folder title caused the error, which might be related to how MatLab accesses files when looking for the function you called.

Hopefully this is clear enough to understand and helps as an alternative if someone else runs into this.

[NOR AZIEYANI]

Hi. I'm trying to understand the above comment. But I still get the same error. Can you checkout this code. Undefined function 'exist' for input arguments of type 'cell'.

wordsstring = regexp(words,'\w+', 'match');
wavdirectory = 'C:\R2013a\bin\Recordings';
[~, number_of_words] = size(wordsstring); %stores number of words in user    
											   % input string                
for m = 1:number_of_words
    filename = [wavdirectory wordsstring{m} '.wav'];
   if(exist(filename, 'file' ~= 0));
   
       filename = [wavdirectory wordsstring{m} '.wav'];
     [y, fs] = audioread(filename); %this tests for Case 1 (base word)
     sound(y, fs);

[Ayswaria Vijayamohan]

Thank you. this was helpful. I faced the same issue. Mo folder name had a '_2' in the name.When the folder name was changed, it worked.