For simplicity above I omitted the noise variance/covariance.
Theoretically,
they are easy to include and in practice I would do so.
Practically, they are unknown and often erratic so
it is a happy coincidence that
*L _{1}*-nomr reduces the sensitivity to the noise variance.

Useing a preconditioner does not change any of the above conclusions.
Then where
so the usual problem
becomes
simply

Stanford Exploration Project

11/12/1997