# zerophase (MathScript RT Module Function)

LabVIEW 2012 MathScript RT模块帮助

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Owning Class: filter design

Requires: MathScript RT Module

## Syntax

zerophase(b)

zerophase(b, a)

zerophase(b, a, w)

zerophase(b, a, w, fs)

zerophase(b, a, n)

zerophase(b, a, n, 'whole')

zerophase(b, a, n, fs)

zerophase(b, a, n, 'whole', fs)

h = zerophase(b)

h = zerophase(b, a)

h = zerophase(b, a, w)

h = zerophase(b, a, w, fs)

h = zerophase(b, a, n)

h = zerophase(b, a, n, 'whole')

h = zerophase(b, a, n, fs)

h = zerophase(b, a, n, 'whole', fs)

[h, f] = zerophase(b)

[h, f] = zerophase(b, a)

[h, f] = zerophase(b, a, w)

[h, f] = zerophase(b, a, w, fs)

[h, f] = zerophase(b, a, n)

[h, f] = zerophase(b, a, n, 'whole')

[h, f] = zerophase(b, a, n, fs)

[h, f] = zerophase(b, a, n, 'whole', fs)

[h, f, p] = zerophase(b)

[h, f, p] = zerophase(b, a)

[h, f, p] = zerophase(b, a, w)

[h, f, p] = zerophase(b, a, w, fs)

[h, f, p] = zerophase(b, a, n)

[h, f, p] = zerophase(b, a, n, 'whole')

[h, f, p] = zerophase(b, a, n, fs)

[h, f, p] = zerophase(b, a, n, 'whole', fs)

## Description

Computes the zero phase response vector and the frequency vector of a filter. If you do not request an output, this function plots the zero phase response of the filter in the current plot window. zerophase(b) is equivalent to zerophase(b, [1], 512). zerophase(b, a) is equivalent to zerophase(b, a, 512).

Examples

## Inputs

Name Description
b Specifies the numerator coefficients of the filter. b is a vector.
a Specifies the denominator coefficients of the filter. a is a vector. The default is [1].
w Specifies the frequency points at which you want to evaluate the zero phase response. If you do not specify w, LabVIEW evaluates the zero phase response at n points equally spaced around the upper half of the unit circle. w is a vector.
fs Specifies the sampling frequency in Hz. fs is a scalar.
n Specifies the number of frequency points. n is a positive integer. The default is 512.
'whole' Directs LabVIEW to evaluate the zero phase response at n points equally spaced around the unit circle.

## Outputs

Name Description
h Returns the zero phase response vector of the filter. h is a real vector.
f Returns the discrete frequency vector in radians/sample that corresponds to h. f is a vector.
p Returns the continuous phase vector of the filter. p is a real vector.

## Details

The following table lists the support characteristics of this function.

 Supported in the LabVIEW Run-Time Engine Yes (if you request output) Supported on RT targets Yes (if you request output) Suitable for bounded execution times on RT Not characterized

## Examples

b = [1, 2];
a = [-1, 1, 1, 3];
n = 32;
[H, F] = zerophase(b, a, n)

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