MATLAB: ” Attempted to access sorted_evalue(0); index must be a positive integer or logical. ” how to remove this?????

MATLAB

 %calculate eigen vector & eigen value of cm = evector & evalue
    evector = dfdb * rvector;
    evalue = diag( rvalue );
    %clear rvector rvalue
    disp( 'Calculated Eigen Vectors & Eigen Values of CM' );
    [sorted_evalue, index] = sort( evalue );            %sorted in acending order
    sorted_evalue = flipud( sorted_evalue );            %rearranged in decending order
    index = flipud( index );                            %rearranged corresponding indies also
    %Now rearrange eigenvectors in the order of rearranged eigen values
    evector( :, 1:nof ) = evector ( :, index );
    smallest_evalue = (1/100) * sorted_evalue(0);            % to obtain the effective eigen values
    for i = 1:nof
        if (sorted_evalue(i) < smallest_evalue )
            break;
        end
        evalue = [ ];
    end
    index = i+1;

Best Answer

The error is du to sorted_evalue(0). In Matlab the indices begin at 1, the 0 is not allowed

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MATLAB: ” Attempted to access sorted_evalue(1); index out of bounds because numel(sorted_evalue)=0. ” how to remove this??

%calculate eigen vector & eigen value of cm = evector & evalue
    if isempty(dfdb) || isempty(rvector)
      error('Need a non-empty dfdb and rvector');
    end
    evector = dfdb * rvector;
    evalue = diag( rvalue );
    %clear rvector rvalue
    disp( 'Calculated Eigen Vectors & Eigen Values of CM' );
    [sorted_evalue, index] = sort( evalue, 'descending' );
    %Now rearrange eigenvectors in the order of rearranged eigen values
    if nof ~= length(index)
      error( sprintf('nof found to be %d, needs to match number of indices = %d', nof, length(index)) );
    end
    evector( :, 1:nof ) = evector ( :, index );
      %sorted-evalue are in descending order. Are you *sure* you want to take a fraction
      %of the largest of them and name that as "smallest_evalue" ??
      smallest_evalue = (1/100) * sorted_evalue(1);            % to obtain the effective eigen values
      %What is the point of this loop? If it is to find the _second_ location where an eigen value
      %is less than 1/100 of the maximum value, then there would be much more straightfoward
      %ways of doing this
      for i = 1:nof
          if (sorted_evalue(i) < smallest_evalue )
              break;
          end
          %and why the heck is evalue left alone if the largest eigenvalue is negative
          %but cleared otherwise? Because the only way that
          % sorted_evalue(1) < sorted_evalue(1)/100 immediately is if sorted_evalue(1) < 0
          evalue = [ ];
      end
      %and if we reached the end of the loop without using the "break" then is it
      %truly okay that index will point past all of the values??
      index = i+1;

MATLAB: Attempted to access sorted_evalue(1); index out of bounds because numel(sorted_evalue)=0. smallest_ev1p = 0.01 * sorted_evalue(1); % to obtain the effective eigen values

Your code fails if evalue is empty at the start of your code. You assume that it is not empty without testing it.

Note: you may wish to consider using sort with 'descending' flag instead of flipud() on the results. You will also need to fix the problem with evalue being empty, but it will make the rest of your code more simple.

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MATLAB: ” Attempted to access sorted_evalue(1); index out of bounds because numel(sorted_evalue)=0. ” how to remove this??

MATLAB: Attempted to access sorted_evalue(1); index out of bounds because numel(sorted_evalue)=0. smallest_ev1p = 0.01 * sorted_evalue(1); % to obtain the effective eigen values

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