释义 |
Self-Adjoint OperatorGiven a differential equation
 | (1) |
where and , the Adjoint Operator is defined by
 | (2) |
In order for the operator to be self-adjoint, i.e.,
 | (3) |
the second terms in (1) and (2) must be equal, so
 | (4) |
This also guarantees that the third terms are equal, since
 | (5) |
so (2) becomes
The Legendre Differential Equation and the equation of Simple Harmonic Motion are self-adjoint, but theLaguerre Differential Equation and Hermite Differential Equation are not.
A nonself-adjoint second-order linear differential operator can always be transformed into a self-adjoint one usingSturm-Liouville Theory. In the special case , (7) gives
 | (8) |
 | (9) |
 | (10) |
 | (11) |
where is a constant of integration.
A self-adjoint operator which satisfies the Boundary Conditions
 | (12) |
is automatically a Hermitian Operator.See also Adjoint Operator, Hermitian Operator, Sturm-Liouville Theory References
Arfken, G. ``Self-Adjoint Differential Equations.'' §9.1 in Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, pp. 497-509, 1985.
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