Zpg function

Zero pole gain model

Create an zero pole gain model of an ARMA filter, or convert other forms to a Zpg model.

Zpg(z, p, g)

as.Zpg(x, ...)

## S3 method for class 'Arma'
as.Zpg(x, ...)

## S3 method for class 'Ma'
as.Zpg(x, ...)

## S3 method for class 'Sos'
as.Zpg(x, ...)

## S3 method for class 'Zpg'
as.Zpg(x, ...)

Arguments

• z: complex vector of the zeros of the model.
• p: complex vector of the poles of the model.
• g: overall gain of the model.
• x: model to be converted.
• ...: additional arguments (ignored).

Returns

A list of class Zpg with the following list elements:

• z: complex vector of the zeros of the model
• p: complex vector of the poles of the model
• g: gain of the model

Details

as.Zpg converts from other forms, including Arma and Ma.

Examples

## design notch filter at pi/4 radians = 0.5/4 = 0.125 * fs
w = pi/4
# 2 poles, 2 zeros
# zeroes at r = 1
r <- 1
z1 <- r * exp(1i * w)
z2 <- r * exp(1i * -w)
# poles at r = 0.9
r = 0.9
p1 <- r * exp(1i * w)
p2 <- r * exp(1i * -w)

zpg <- Zpg(c(z1, z2), c(p1, p2), 1)
zplane(zpg)
freqz(zpg)

## Sharper edges: increase distance between zeros and poles
r = 0.8
p1 <- r * exp(1i * w)
p2 <- r * exp(1i * -w)
zpg <- Zpg(c(z1, z2), c(p1, p2), 1)
zplane(zpg)
freqz(zpg)

See Also

See also Arma

Author(s)

Tom Short, tshort@eprisolutions.com ,

adapted by Geert van Boxtel, gjmvanboxtel@gmail.com .