spectral function [closed]

How do you obtain the spectral function for advection equation in one dimension? 2.How about 2D? thanks a lot

-
Please try <a href="math.stackexchange.com/">math stackexchange</a> for math problems and add both the equations and your definition of "spectral function" to your post over there :-) –  Tim van Beek May 10 '11 at 7:22
Please improve the question, otherwise it will be closed. –  mbq May 10 '11 at 10:04
This question can be re-opened if it is improved by being more clear about what you mean by "spectral function" in this context (the phrase appears repeatedly in different parts of physics and has subtly different meanings), and stating the basic equation explicitly in the question text. MathJax is available to render LaTeX style equations. –  dmckee May 29 '11 at 2:22