isreal

Verify that discrete-time filter System object is real

Syntax

flag = isreal(sysobj)

Description

flag = isreal(sysobj) determines if the filter coefficients are real. If the filter coefficients are real, isreal returns a logical 1. If the filter coefficients are complex, isreal returns a logical 0. Complex filters have one or more coefficients with nonzero imaginary parts.

Examples

Check if Filter Coefficients Are Real

Create a dsp.BiquadFilter System object™. Pass a fixed-point input to the object. Test the coefficients of the fixed-point filter to see if they are strictly real.

d = fdesign.lowpass('n,fp,ap,ast',5,0.4,0.5,20);
biquadFilter = design(d,'ellip','SystemObject',true);
IsRealBefore = isreal(biquadFilter)

IsRealBefore = logical
   1

Pass a fixed-point input to the object.

fiInput = fi(randn(1000,2),1,32,16);
fiOutput = biquadFilter(fiInput);
IsRealAfter = isreal(biquadFilter)

IsRealAfter = logical
   1

The isreal function returns a value of 1, indicating that the filter coefficients are real.

Input Arguments

sysobj — Input filter

filter System object™

Input filter, specified as one of the following filter System objects:

• dsp.AllpassFilter

• dsp.AllpoleFilter

• dsp.BiquadFilter

• dsp.CICCompensationDecimator

• dsp.CICCompensationInterpolator

• dsp.CICDecimator

• dsp.CICInterpolator

• dsp.CoupledAllpassFilter

• dsp.Differentiator

• dsp.FarrowRateConverter

• dsp.FilterCascade

• dsp.FIRDecimator

• dsp.FIRFilter

• dsp.FIRHalfbandDecimator

• dsp.FIRHalfbandInterpolator

• dsp.FIRInterpolator

• dsp.FIRRateConverter

• dsp.FourthOrderSectionFilter

• dsp.HighpassFilter

• dsp.IIRFilter

• dsp.IIRHalfbandDecimator

• dsp.IIRHalfbandInterpolator

• dsp.LowpassFilter

• dsp.NotchPeakFilter

• dsp.SOSFilter

• dsp.VariableBandwidthFIRFilter

• dsp.VariableBandwidthIIRFilter

Output Arguments

flag — Flag to determine whether filter coefficients are real

1 | 0

Flag to determine whether the filter coefficients are real, returned as a logical scalar. If the filter coefficients are real, isreal returns a logical 1, else it returns a logical 0.

Data Types: logical