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Valid input arguments and values for specification object and method


OPTS = designopts(D,METHOD)


OPTS = designopts(D,METHOD) returns a structure array with the default design parameters used by the design method METHOD. METHOD must be one of the options returned by designmethods.

Use help(D,METHOD) to get a description of the design parameters.

If you have DSP System Toolbox™ software installed, OPTS has the SystemObject property if at least one of the structures available for that design method is supported by System objects. However, not all structures for that design method are supported by System objects.


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Create a lowpass filter with a numerator and denominator order of 10 and a 3-dB frequency of 0.2π rad/sample. Obtain the default design parameters for a Butterworth design. Test whether the filter structure is a direct-form II biquad.

D = fdesign.lowpass('Nb,Na,F3dB',10,10,0.2);
OPTS = designopts(D,'butter')
OPTS = struct with fields:
    FilterStructure: 'df2sos'
       SOSScaleNorm: ''
       SOSScaleOpts: [1x1 fdopts.sosscaling]
       SystemObject: 0

if isequal(OPTS.FilterStructure,'df2sos')
    fprintf('The default filter structure is Direct-Form II\n');
    fprintf('with second-order sections.\n');
The default filter structure is Direct-Form II
with second-order sections.

Version History

Introduced in R2009a