#### 29.2.1 Finite impulse response system interface functions

— Function File: fir2sys (num, tsam, inname, outname)

> construct a system data structure from FIR description

> Inputs

> num
>   vector of coefficients [c0, c1, ..., cn] of the SISO FIR transfer function C(z) = c0 + c1*z^(-1) + c2*z^(-2) + ... + cn*z^(-n)
> tsam
>   sampling time (default: 1)
> inname
>   name of input signal; may be a string or a list with a single entry.
> outname
>   name of output signal; may be a string or a list with a single entry.

> Output

> sys
>   system data structure

> Example

>               octave:1> sys = fir2sys([1 -1 2 4],0.342,\
>               > "A/D input","filter output");
>               octave:2> sysout(sys)
>               Input(s)
>                       1: A/D input

>               Output(s):
>                       1: filter output (discrete)

>               Sampling interval: 0.342
>               transfer function form:
>               1*z^3 - 1*z^2 + 2*z^1 + 4
>               -------------------------
>               1*z^3 + 0*z^2 + 0*z^1 + 0

— Function File: [c, tsam, input, output] = sys2fir (sys)

> Extract FIR data from system data structure; see `fir2sys` for parameter descriptions.