"""
Signal Processing Tools
=======================

 Convolution:

    convolve      --  N-dimensional convolution.
    correlate     --  N-dimensional correlation.
    fftconvolve   --  N-dimensional convolution using the FFT.
    convolve2d    --  2-dimensional convolution (more options).
    correlate2d   --  2-dimensional correlation (more options).
    sepfir2d      --  Convolve with a 2-D separable FIR filter.

 B-splines:

    bspline       --  B-spline basis function of order n.
    gauss_spline  --  Gaussian approximation to the B-spline basis function.
    cspline1d     --  Coefficients for 1-D cubic (3rd order) B-spline.
    qspline1d     --  Coefficients for 1-D quadratic (2nd order) B-spline.
    cspline2d     --  Coefficients for 2-D cubic (3rd order) B-spline.
    qspline2d     --  Coefficients for 2-D quadratic (2nd order) B-spline.
    spline_filter --  Smoothing spline (cubic) filtering of a rank-2 array.

 Filtering:

    order_filter  --  N-dimensional order filter.
    medfilt       --  N-dimensional median filter.
    medfilt2      --  2-dimensional median filter (faster).
    wiener        --  N-dimensional wiener filter.

    symiirorder1  --  2nd-order IIR filter (cascade of first-order systems).
    symiirorder2  --  4th-order IIR filter (cascade of second-order systems).
    lfilter       --  1-dimensional FIR and IIR digital linear filtering.

    deconvolve    --  1-d deconvolution using lfilter.

    hilbert       -- Compute the analytic signal of a 1-d signal.
    get_window    -- Create FIR window.

    detrend       -- Remove linear and/or constant trends from data.
    resample      -- Resample using Fourier method.

 Filter design:

    remez         -- Optimal FIR filter design.
    firwin        -- Windowed FIR filter design.
    iirdesign     -- IIR filter design given bands and gains.
    iirfilter     -- IIR filter design given order and critical frequencies.
    freqs         -- Analog filter frequency response.
    freqz         -- Digital filter frequency response.

    unique_roots  -- Unique roots and their multiplicities.
    residue       -- Partial fraction expansion of b(s) / a(s).
    residuez      -- Partial fraction expansion of b(z) / a(z).    
    invres        -- Inverse partial fraction expansion.

 Matlab-style IIR filter design:

    butter (buttord)  -- Butterworth
    cheby1 (cheb1ord) -- Chebyshev Type I
    cheby2 (cheb2ord) -- Chebyshev Type II
    ellip (ellipord)  -- Elliptic (Cauer)
    bessel            -- Bessel (no order selection available -- try butterod)

 Linear Systems:

    lti     -- linear time invariant system object.
    lsim    -- continuous-time simulation of output to linear system.
    impulse -- impulse response of linear, time-invariant (LTI) system.
    step    -- step response of continous-time LTI system.

 LTI Reresentations:

    tf2zpk -- transfer function to zero-pole-gain.
    zpk2tf -- zero-pole-gain to transfer function.
    tf2ss  -- transfer function to state-space.
    ss2tf  -- state-pace to transfer function.
    zpk2ss -- zero-pole-gain to state-space.
    ss2zpk -- state-space to pole-zero-gain.

 Waveforms:

    sawtooth   -- Periodic sawtooth
    square     -- Square wave
    gausspulse -- Gaussian modulated sinusoid
    chirp      -- Frequency swept cosine signal

 Window functions:

    boxcar           -- Boxcar window
    triang           -- Triangular window
    parzen           -- Parzen window
    bohman           -- Bohman window
    blackman         -- Blackman window
    blackmanharris   -- Minimum 4-term Blackman-Harris window
    nuttall          -- Nuttall's minimum 4-term Blackman-Harris window
    flattop          -- Flat top window
    bartlett         -- Bartlett window
    hann             -- Hann window
    barthann         -- Bartlett-Hann window
    hamming          -- Hamming window
    kaiser           -- Kaiser window
    gaussian         -- Gaussian window
    general_gaussian -- Generalized Gaussian window
    slepian          -- Slepian window

 Wavelets:

    daub    -- return low-pass filter for daubechies wavelets
    qmf     -- return quadrature mirror filter from low-pass
    cascade -- compute scaling function and wavelet from coefficients
"""

postpone_import = 1
