isreal

Determine whether filter uses real coefficients

Syntax

isreal(hd)
isreal(hs)

Description

isreal(hd) returns 1 (or true) if all filter coefficients for the filter hd are real, and returns 0 (or false) otherwise. Complex filters have one or more coefficients with nonzero imaginary parts.

isreal(hs) determines whether the filter coefficients of the filter System object™ hs are real, returning 1 if true and 0 if false.

Note

Quantizing a filter cannot make a real filter into a complex filter.

Examples

collapse all

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

isreal returns a 1, indicating that the filter coefficients are real.

Introduced in R2011a