MATLAB Function Reference |

Wilkinson's eigenvalue test matrix

**Syntax**

**Description**

```
W = wilkinson(n)
```

returns one of J. H. Wilkinson's eigenvalue test matrices. It is a symmetric, tridiagonal matrix with pairs of nearly, but not exactly, equal eigenvalues.

**Examples**

wilkinson(7) ans = 3 1 0 0 0 0 0 1 2 1 0 0 0 0 0 1 1 1 0 0 0 0 0 1 0 1 0 0 0 0 0 1 1 1 0 0 0 0 0 1 2 1 0 0 0 0 0 1 3

The most frequently used case is `wilkinson(21)`

. Its two largest eigenvalues are both about 10.746; they agree to 14, but not to 15, decimal places.

**See Also**

who, whos | winopen |