MATLAB: Performance using temporary boolean filter

logical?

In a situation where I need to use a logical filter (simply a vector of logical) 3 times in succession, am I likely to get a performance improvement by creating a temporary variable to hold the filter and then referring to that where necessary as opposed to just repeating the filter expression explicitly? e.g. I could define say: filter=(floor(x)==y); then do something to A(filter), B(filter) and C(filter) or I could do something to A(floor(x)==y), B(floor(x)==y) and C(floor(x)==y)

Best Answer

A(floor(x)==y) creates the temporary array floor(x)==y explicitly. Therefore doing this three times needs more resources than making the comparison once only. Therefore A(filter) etc. is faster.

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MATLAB: How to properly use the Cascaded integrator-comb (CIC) filter in the cascade filter structure to filter a signal in Filter Design Toolbox 3.0 (R14)

Currently, the CIC filters only work with the built-in signed integer data types such as INT8, INT16, and INT32.

The CIC filter must come first in the cascade. The following code shows how the code should be written:

L = 7;     % variable interpolation factor
N = 4;     % number of stages
hcic = mfilt.cicinterp(L,1,N);
dcGain = L*gain(hcic);
hscalar = dfilt.scalar(1/dcGain);
hscalar.Arithmetic = 'fixed';
Hcas = cascade(hcic,hscalar); % Note that the CIC comes first
x = randn(1,64);
y = filter(Hcas,int16(x));

Please note that the CIC filter (hcic) must come first in the cascade. The reason is that output of the CIC filter is an INT16 in this case and the hscalar filter can interpret that data type. In Filter Design Toolbox 3.0 (R14) the CIC filters do not work with the output that is an embedded.fi object. In this example, the output of the hscalar filter is an embedded.fi object.

MATLAB: FIR filters and the delay associated with them

See if using the filtfilt (link) function or the zerophase (link) function will do what you want.

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Related Solutions

MATLAB: How to properly use the Cascaded integrator-comb (CIC) filter in the cascade filter structure to filter a signal in Filter Design Toolbox 3.0 (R14)

MATLAB: FIR filters and the delay associated with them

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