MATLAB: Subscript indices must either be real positive integers or logicals.

integration

    if true
      % code
    end  
  function [Ex,Ey,Ez]=coordxtr(Edof,Coord,Dof,nen)
  %[Ex,Ey,Ez]=coordxtr(Edof,Coord,Dof,nen)
  %-------------------------------------------------------------


  % PURPOSE
  %    Extract nodal coordinate data from the global coordinate 
  %    matrix for a number of elements with equal number of 
  %    element nodes and dof's. 
  %





  % INPUT:  Edof :  topology matrix , dim(t)= nie x ned+1
  %                         nie= number of identical elements
  %                           ned= number of element dof's  
  %
  %         Coord: global coordinate matrix 
  %
  %         Dof:   global nodal dof matrix 
  %
  %         nen:   number of element nodes
  %
  % OUTPUT: Ex,Ey,Ez : element coordinate matrices
  %         Ex=[x1 x2 ...xnen;    one row for each element
  %             ...     ...  ;
  %             nel     ...  ]  
  %             dim= nel x nen ;   nel:number of elemnts 
  %-------------------------------------------------------------
% LAST MODIFIED: P-E Austrell 1993-10-14 
% Copyright (c)  Division of Structural Mechanics and
%                Department of Solid Mechanics.
%                Lund Institute of Technology
%-------------------------------------------------------------
    [nel,dum]=size(Edof);
     ned=dum-1;
    [n,nsd]=size(Coord);
    [n,nd]=size(Dof);
     nend=ned/nen;
 %
    for i = 1:nel
       nodnum=zeros(1,nen);
       for j = 1:nen
          check=Dof(:,1:nend)-ones(n,1)*Edof(i,(j-1)*nend+2:j*nend+1);
          [indx,dum]=find(check==0);
           if length(indx)>0
              nodnum(j)=indx(1);
           else
              nodnum(j)=0;
           end
      end
 %       
          Ex(i,:)=Coord(nodnum,1)';
       if nsd>1
          Ey(i,:)=Coord(nodnum,2)';
       end
       if nsd>2    
          Ez(i,:)=Coord(nodnum,3)';
       end
    end  
%--------------------------end--------------------------------
what should I do?
Thank you guys
??? Subscript indices must either be real positive integers or logicals.
    Error in ==> coordxtr at 49
              Ex(i,:)=Coord(nodnum,1)';

Best Answer

In MATLAB indexing starts at 1, not 0, so setting nodnum to zero
nodnum(j)=0;
doesn't make sense if you are going to be indexing with it.
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