# Eigen functions & eigen vectors

1. Nov 19, 2008

### Amith2006

In Quantum mechanics, we frequently deal with eigen value equations. When we speak of eigen value equations, we come across terms like eigen values,eigen vectors,eigen functions etc. When an operator is operated on certain quantities we get the same quantity multiplied by a constant. These quantities are interchangeably referred as eigen vectors and eigen functions. But do they mean the same? Is it something like, we call it as eigenfunctions in Schrodinger formalism and eigenvectors or eigenkets in Heisenberg formalism or is there a ma thematical difference between the 2?

2. Nov 19, 2008

### Fredrik

Staff Emeritus
They are the same. It would be weird to use "eigenket" when you're not using bra-ket notation, and it would be weird to use "eigenfunction" if you're talking about a vector that isn't actually a function, but other than that they're the same. The term "eigenstate" is also used interchangeably with the others. That's actually a little bit weird since a "state" is represented by an equivalence class of vectors. (Two vectors are equivalent if one of them is a complex number times the other).

Last edited: Nov 19, 2008