Add scipy.signal.iirdesign()

applications/lofar2/model/pfb_os/dsp_study_erko.txt

@@ -449,14 +449,15 @@
    . Optimized IIR design methods, iteratively adjust coefficients to achieve
      a specified arbitrary frequency response (f_pass, f_stop, r_pass_dB,
      r_stop_dB bands).
-     . scipy.signal.cheby2(), ripple in stop band
-     . scipy.signal.cheby1(), ripple in pass band
-     . scipy.signal.butter(), maximally flat in pass band, decay in stop band
-     . scipy.signal.ellip(N, rp, rs, Wn): Elliptic (Cauer) digital and analog
-       filter design. As rp approaches 0, the elliptical filter becomes a
-       Chebyshev type II filter (cheby2). As rs approaches 0, it becomes a
-       Chebyshev type I filter (cheby1). As both approach 0, it becomes a
-       Butterworth filter (butter).
+     . scipy.signal.iirdesign(), can do all of:
+       . scipy.signal.cheby2(), ripple in stop band
+       . scipy.signal.cheby1(), ripple in pass band
+       . scipy.signal.butter(), maximally flat in pass band, decay in stop band
+       . scipy.signal.ellip(N, rp, rs, Wn): Elliptic (Cauer) digital and analog
+         filter design. As rp approaches 0, the elliptical filter becomes a
+         Chebyshev type II filter (cheby2). As rs approaches 0, it becomes a
+         Chebyshev type I filter (cheby1). As both approach 0, it becomes a
+         Butterworth filter (butter).
 
 6) Discrete Fourier Transform (DFT)
 - The N roots of unity [JOS1 3.12, 5.1, PROAKIS 5.1.3, LYONS 4.3]. Note JOS