| # A squared linear function Symmetric Matrices > Definitions > Example A squared linear function is a quadratic function of the form for some vector . The function vanishes on the space orthogonal to , which is the hyperplane defined by the single linear equation . Thus, in effect this function is really one-dimensional: it varies only along the direction .
| Level sets and graph of a dyadic quadratic function, corresponding to the vector . The function is constant along hyperplanes orthogonal to .