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[[File:Chebyshev_s_plane.svg|right|thumb|The ''s''-plane poles and zeros of a 5th-order [[Chebyshev_filter#Type_II_Chebyshev_filters|Chebyshev type II lowpass filter]] to be appoximated as a discrete-time filter]]
[[File:Chebyshev_mapped_z_plane.svg|right|thumb|The ''z''-plane poles and zeros of the discrete-time Chebyshev filter, as mapped into the z-plane using the matched Z-transform method with ''T'' = 0.1 second. The labeled frequency points and band-edge dotted lines have also been mapped through the function exp(''sT''), to show how frequencies along the ''i%omega;'' axis in the ''s''-plane map onto the unit circle in the ''z''-plane.]]
The '''matched Z-transform method''', also called the '''pole–zero mapping'''<ref>
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Alternative methods include the [[bilinear transform]] and [[impulse invariance]] methods.
[[File:Chebyshev_responses.svg|left|thumb|350px|Responses of the filter (dashed), and its discrete-time approximation (solid), for nominal cutoff frequency of 1 Hz, sample rate 10 Hz. The discrete-time filter does not reproduce the Chebyshev equiripple property in the stopband due to the interference from cyclic copies of the passband.]]
==References==
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