Effective bandwidth of 2-D functions that can be expressed as a linear combination of orthogonal functions

The authors investigate bounds on the two-dimensional function f(x,y) that can be expressed as a linear combination of an orthogonal set of functions (q/sub nm/(x,y)) in the mean. Each function q/sub nm/(x,y) has the property of being separable. Each of these functions is bandlimited. Effective bandwidth expressions are derived on the basis of a given error criterion.<
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