Actually, the matrix is an adjacency matrix of a network. The code is:

```
A1 = GridGraph({20, 20}, PlotLabel -> "20*20 nodes",
VertexLabels -> "Name")
A = AdjacencyMatrix(A1);
```

I want to calculate the eigenvalue of A and its eigenvector.

I have tried the normal function such as Eigenvalues and Eigenvectors. But it need much time and may not get a result(my laptop have not complete the calculation yet.)

The code is:

```
(Lambda) = N(Eigenvalues(Normal(A), 1))((1));
uA = N(Eigenvectors(Normal(A), 1))((1));
```

I want to know whether there is a method or parameter to reduce the time.