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In Guitton (2001) I presented
an efficient algorithm that attenuates coherent noise based on the
spatial predictability of noise and signal. I called this algorithm the
subtraction method. In this paper I show that
the subtraction approach is closely related to another described
method, the filtering method
Brown and Clapp (2000); Clapp and Brown (2000); Soubaras (1994); Spitz (1999) if I use a preconditioning strategy Claerbout and Fomel (2001).
In a second part I prove that the Spitz estimate for the signal
PEF Spitz (1999) makes the inversion of the Hessian stable
in the subtraction method.

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** Up:** Guitton: Preconditioning and Hessian
** Previous:** Guitton: Preconditioning and Hessian
Stanford Exploration Project

6/7/2002