1. A method for determining effective tap values for a digital filter, comprising: generating a first plurality of vectors, wherein each of the first plurality of vectors represents a set of tap values for the filter at a first resolution; selecting a best vector from the first plurality of vectors according to a first performance metric; generating a second plurality of vectors within a threshold distance of the selected best vector, wherein each of the second plurality of vectors represents a set of tap values for the filter at a second resolution that is higher than the first resolution; and selecting a best vector from the second plurality of vectors according to a second performance metric.