Function FILTER_BANK

Package

filters

Short description

Create a cell array of filter banks

Usage

Input 

    N (int): The size of the input data.
    options (struct): Filter parameters, see below.

Output 

    filters (struct): A cell array of filter banks corresponding to the
      data size N and the filter parameters in options.

Description 

    The behavior of the function depends on the value of options.filter_type,
    which can have the following values:
       'morlet_1d', 'gabor_1d': Calls MORLET_FILTER_BANK_1D.
       'spline_1d': Calls SPLINE_FILTER_BANK_1D.
       'selesnick_1d': Calls SELESNICK_FILTER_BANK_1D.
    The filter parameters in options are then passed on to these functions.
    If multiple filter banks are desired, multiple parameters can be supplied
    by providing a vector of parameter values instead of a scalar (in the 
    case of filter_type and filter_format, these have to be cell arrays).
    The function will then split the options structure up into several 
    parameter sets and call the appropriate filter bank function for each one
    returning the result as a cell array. If a given field does not have 
    enough values to specify parameters for all filter banks, the last ele-
    ment is used to extend the field as needed.
    The specific parameters vary between filter bank types, but the follow-
    ing are common to all types:
       options.filter_type: Can be 'morlet_1d', 'gabor_1d', 'spline_1d',
          or 'selesnick_1d' (default 'morlet_1d').
       options.boundary: Sets the boundary conditions of the wavelet trans-
          form. If 'symm', symmetric boundaries will be used, if 'per', per-
          iodic boundaries will be used (default 'symm').
       options.precision: Either 'double', or 'single'. Determines the preci-
          sion of the filters stored and consequently that of the resulting
          wavelet and scattering transform (default 'double').
       options.filter_format: Specifies the format in which the filters are 
          stored. Three formats are available:
             'fourier': Filters are stored as Fourier transforms defined
                 over the whole frequency domain of the signal.
             'fourier_multires': Filters are stored as Fourier transforms 
                 defined over the frequency domain of the signal at all
                 resolutions. This requires much more memory, but speeds up
                 calculations significantly.
              'fourier_truncated': Stores the Fourier coefficients of each
                 filter on the support of the filter, reducing memory
                 consumption and increasing speed of calculations (default).
    For parameters specific to the filter bank type, see the documentation
    for MORLET_FILTER_BANK_1D, SPLINE_FILTER_BANK_1D, and
    SELESNICK_FILTER_BANK_1D.

See also

List of all packages