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Methods available for designing filter from specification object


M = designmethods(D)
M = designmethods(D,'default')
M = designmethods(D,TYPE)
M = designmethods(D,'full')
Ms = designmethods(D,...,'SystemObject',sysobjflag)


M = designmethods(D) returns the available design methods for the filter specification object, D, and the current value of the Specification property.

M = designmethods(D,'default') returns the default design method for the filter specification object D and the current value of the Specification property.

M = designmethods(D,TYPE) returns either the TYPE design methods that apply to D. TYPE can be either 'FIR' or 'IIR'.

M = designmethods(D,'full') returns the full name for each of the available design methods. For example, designmethods with the 'full' argument returns Butterworth for the butter method.

Ms = designmethods(D,...,'SystemObject',sysobjflag) returns the available design methods for designing filter System objects when sysobjflag is true. To use System objects, you must have the DSP System Toolbox™ product installed. When sysobjflag is false, the function checks methods for creating dfilt objects, as described previously. Design methods and design options for filter System objects are not necessarily the same as those for dfilt objects.


Construct a lowpass filter specification object and determine the valid design methods. Obtain detailed command line help on the Chebyshev type I design method.

D =fdesign.lowpass('Fp,Fst,Ap,Ast',500,600,0.5,60,1e4);
M = designmethods(D)

The last line of the example is equivalent to help(D,'cheby1').

If you have DSP System Toolbox software installed, use the 'SystemObject',sysobjflag syntax to return design methods for a filter System object:

Ms = designmethods(D,'SystemObject',true);

Introduced in R2009a

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