Projection (algebra linear)

In algebra linear e analyse functional, un projection es un transformation linear P de un spatio de vectores a ipse tal que P² = P.

Le equation de autovalores (eigenvalue)

${\displaystyle A|n>=a_{n}|n>}$

defini

${\displaystyle P_{n}=|n><n|,}$

${\displaystyle A=\sum _{n}a_{n}P_{n}=\sum _{n}a_{n}|n><n|.}$

${\displaystyle I=\sum _{n}P_{n}=\sum _{n}|n><n|.}$