Index exceeds matrix dimensions.

Error in the command window

li=X1(clsi,:);

This how the program looks

function [W ,B]=scattermat(X1,y1)
%FUNCTION THAT CALCULATES SCATTER MATRIX:
%   B:BETWEEN  CLASS SCATTER MATRIX
%   W:WITHIN CLASS SCATTER MATRIX
%

      [~, l]=size(X1);         %CALCULATE SIZE OF DATA
      clases=unique(y1);          %GET VECTOR OF CLASSES
      total_clases=length(clases); %HOW MANY CLASSES
      B=zeros(l,l);              %INIT B AND W
      W=zeros(l,l);           
      ovrmean=mean(X1);    %MEAN OVER ALL DATA
      for i=1:total_clases
          clsi = find(y1==clases(i)); %GET DATA FOR EACH CLASS
          display(clsi);   
          li=X1(clsi,:);
          mclsi=mean(li);                       %MEAN PER CLASS
          li=li-repmat(mclsi,length(clsi),1);   %Xi-MeanXi
          B=B+li'*li;                            %CALCULATE B
          W=W+length(clsi)*(mclsi-ovrmean)'*(mclsi-ovrmean); %CALCULATE W
      end
  end

How do I resolve this issue ??? I am new to matlab. Please help me out.

Answer 1

[Walter Roberson]

That could happen if the input vector y1 is not the same length as the number of rows in the input X1.