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1 Introduction
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2 Low pass and high pass filters
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Some business cycle researchers
have argued for the desirability of such sharp filters, referring to them as ideal.
The use of a sharp band pass filter involves the notion that the underlying
cyclical component itself is in fact
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Another class of Butterworth filters is gven by replacing the sine function in equation (5)
by a tangent fu nction; see Gom ez (2000). We restrict attention to sine fun ction filters as they
are most easily linked to unobserved com ponents m odels.
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