Error "not enough input arguments" in length function

I am trying to run a code but receiving an error at the 4th line with 'not enough input' for the length function. What can be inserted in further to remove the error.

function [coef] = ComputeCurve_EDIT (SUBJRAWSubj1S1)
coef = [];
i = 1; % matrix row index
NRrows = Length (SUBJRAWSubj1S1);
while (i <= NRrows) % while not end of matrix
   x = []; % initialize to-be-filled vectors
   y = [];
   xnorm = [];
   ynorm = [];
   n = i; % keeps track of the number of samples on a given trial
   trialNR = SUBJRAWSubj1S1 (i, 1);
   while (SUBJRAWSubj1S1 (i, 1) == trialNR) % fill x and y coordinate vectors
    x = [x; SUBJRAWSubj1S1 (i, 2)];
   	y = [y; SUBJRAWSubj1S1 (i, 3)];
    i = i + 1;
    if (i> NRrows)
      break
    end
   end

[dpb]

Spell "length" correctly ... MATLAB is case-sensitive and you capitalized it...

NB: length() is potentially dangerous unless it is used on only vectors -- it returns max(size(x)) which for a 2D input can be either size(x,1) or size(x,2) depending on whether is taller or wider in aspect.

Use size(x,D) for the dimension of interest for more reliable code.

[Tanaya Chatterjee]

hello, thank you for your response.

I have a data with three columns with around 150 rows. trial number, x position and y position.

I want matlab to screen throught the length/ size of the rows in the columns and assign that variable as Nrows. What do you think should be the 'D' in size(x,D) because when i try size(x) it is returning not enough input argument.

Thank you for your help!

[dpb]

As said, if you are concerned about the rows, that's dimension 1 so the 'D' argument to size would be one.