
Eigenvalues and eigenvectors
Linear algebra talks about types of functions called transformations. In that context, an eigenvector is a vector—different from the null vector—which does not change direction after the transformation. The vector may change its length, or become zero. The eigenvalue is the value of the vector's change in length, and is typically denoted by the symbol. The word "eigen" is a German word, which means "own" or "typical".