# Question:what does Error, (in LinearAlgebra:-Eigenvectors) multiplicity mismatch mean?

## Question:what does Error, (in LinearAlgebra:-Eigenvectors) multiplicity mismatch mean?

Maple 2019

I was trying this in Maple to check Mathematica's result, and got this error. But googling and the link Maple gives lead to nothing.

Any one knows why Maple gives this error message here?

```restart;

phi:=Pi;
A := <
<0, 0, exp(I*k1) + m1, exp(I*k2) + m2>|
<0, 0, exp(I*phi)*(exp(-I*k2) + m2), exp(-I*k1) + m1>|
<exp(-I*k1) + m1, exp(-I*phi)*(m2 + exp(I*k2)), 0, 0>|
<exp(-I*k2) + m2, exp(I*k1) + m1, 0, 0>
>:
LinearAlgebra:-Eigenvectors(A)

```

Error, (in LinearAlgebra:-Eigenvectors) multiplicity mismatch

fyi, Mathemtica's result is

```ClearAll[k1, m1, m2, k2];
Phi = Pi;
H = {{0, 0, Exp[I k1] + m1, Exp[I k2] + m2}, {0, 0,
Exp[I Phi] (Exp[-I k2] + m2), Exp[-I k1] + m1}, {Exp[-I k1] + m1,
Exp[-I Phi] (m2 + Exp[I k2]), 0, 0}, {Exp[-I k2] + m2,
Exp[I k1] + m1, 0, 0}};
Eigenvectors[H]```

I tried tracing in Maple, but so far no useful result:

```infolevel[all]:=5;
LinearAlgebra:-Eigenvectors(A)

.
.
.
simplify/size: [1/(2+m1^2+m2^2+2*m1*((1/2)*exp(I*k1)+(1/2)*exp(-I*k1))+2*m2*((1/2)*exp(I*k2)+(1/2)*exp(-I*k2)))^(1/2) exp(-I*k1) exp(-I*k2) exp(I*k1) exp(I*k2) _t[1] _t[2] m1 m2 k1 k2]
simplify/size: [exp(-I*k1) exp(-I*k2) exp(I*k1) exp(I*k2) m1 m2 _t[1] _t[2] k1 k2]
simplify/size: [1/(2+m1^2+m2^2+2*m1*cos(k1)+2*m2*cos(k2))^(1/2) exp(-I*k1) exp(-I*k2) cos(k1) cos(k2) _t[1] _t[2] m1 m2 k1 k2]
simplify/do: applying  commonpow  function to expression
simplify/do: applying  power  function to expression
simplify/do: applying simplify/size function to expression

Error, (in LinearAlgebra:-Eigenvectors) multiplicity mismatch
```

Maple 2019.2.1 on windows

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