MATLAB: Eigenvalue matrix error subscript

matrix eigenvalue

hi , I suppose this should be easy but I am getting error
">> donnel Subscript indices must either be real positive integers or logicals.
Error in donnel (line 18) A=[(omega^2)-(lamda^2)-((1-v^2)/2)*n^2 n*lamda*(1+v)/2 v*lamda;
I just want to calc the eig(A) afterward…thanks
 syms f
  R=0.306;
  L=0.21;
  E=7.1E10;
  v=0.3296;
  p=2700;
  h=0.001;
K=(h^2)/(12*R^2);
w=2*pi*f;
m=1;
n=1;
lamda=1i*m*pi*R/L;
omega=sqrt(((1-v^2)*p*w^2*R^2)/E);
A=[(omega^2)-(lamda^2)-((1-v^2)/2)*n^2 n*lamda*(1+v)/2 v*lamda;
    n*lamda*(1+v)/2 (1-v)*lamda^2-n^2+omega^2 -n;
    -v*lamda n (-omega^2)+1+K((lamda^2)+(n^2))^2];

Best Answer

in the last line your are trying to index K with
K((lamda^2)+(n^2))
this turns out to be a negative number.
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