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Please note that the recommended version of Scilab is 2023.1.0. This page might be outdated.
See the recommended documentation of this function

# frmag

magnitude of FIR and IIR filters

### Calling Sequence

```[xm,fr]=frmag(sys,npts)
[xm,fr]=frmag(num,den,npts)```

### Arguments

sys

a single input, single output discrete transfer function, or a polynomial or the vector of polynomial coefficients, the filter.

num

a polynomial or the vector of polynomial coefficients, the numerator of the filter

den

a polynomial or the vector of polynomial coefficients, the denominator of the filter (the default value is 1).

npts

integer, the number of points in frequency response.

xm

vector of magnitude of frequency response at the points `fr`.

fr

points in the normalized frequency domain where magnitude is evaluated.

### Description

calculates the magnitude of the frequency responses of FIR and IIR filters. The filter description can be one or two vectors of coefficients, one or two polynomials, or a single output discrete transfer function.

the frequency discretization is given by `fr=linspace(0,1/2,npts)`.

### Examples

```hz=iir(3,'bp','cheb1',[.15 .25],[.08 .03]);
[hzm,fr]=frmag(hz,256);
plot(fr,hzm)
hz=iir(3,'bp','ellip',[.15 .25],[.08 .03]);
[hzm,fr]=frmag(hz,256);
plot(fr,hzm,'r')```