MATLAB: Getting an error “INDEX OUT OF BOUNDS” in the matlab program. Please help.

matlab fem

%%Loop for chi values for icounter=-1:1:1 chi=(icounter); end
%%Shape function for axial effect N1(chi)=(-1/2)*chi*(1-chi); N2(chi)=(1+chi)*(1-chi); N3(chi)=(1/2)*chi*(1+chi);
%%First Derivatives of Shape Function N1=diff(N1(chi),chi); N2=diff(N2(chi),chi); N3=diff(N3(chi),chi);
%%%%Second Derivatives of Shape Function N11=diff(N1(chi),chi,2); Attempted to access N1(1); index out of bounds because numel(N1)=0.(ERROR) N22=diff(N2(chi),chi,2); N33=diff(N3(chi),chi,2);

Best Answer

This loop loop
for icounter=-1:1:1 
    chi=(icounter); 
end
chi=1
and When you calculate the following diff
   N1(chi)=(-1/2)*chi*(1-chi); 
    N2(chi)=(1+chi)*(1-chi);
1-chi terms lead to zero, so N1(chi) is null and you try to diff N1(chi) (Null) with respect to 1.
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