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Owning Class: filter design
Requires: MathScript RT Module
[b, a] = iir_butter(n, w)
[b, a] = iir_butter(n, w, 's')
[b, a] = iir_butter(n, [w1, w2])
[b, a] = iir_butter(n, [w1, w2], 's')
[b, a] = iir_butter(n, w, option)
[b, a] = iir_butter(n, w, option, 's')
[b, a] = iir_butter(n, [w1, w2], 'stop')
[b, a] = iir_butter(n, [w1, w2], 'stop', 's')
[z, p, k] = iir_butter(n, w)
[z, p, k] = iir_butter(n, w, 's')
[z, p, k] = iir_butter(n, [w1, w2])
[z, p, k] = iir_butter(n, [w1, w2], 's')
[z, p, k] = iir_butter(n, w, option)
[z, p, k] = iir_butter(n, w, option, 's')
[z, p, k] = iir_butter(n, [w1, w2], 'stop')
[z, p, k] = iir_butter(n, [w1, w2], 'stop', 's')
[as, bs, cs, ds] = iir_butter(n, w)
[as, bs, cs, ds] = iir_butter(n, w, 's')
[as, bs, cs, ds] = iir_butter(n, [w1, w2])
[as, bs, cs, ds] = iir_butter(n, [w1, w2], 's')
[as, bs, cs, ds] = iir_butter(n, w, option)
[as, bs, cs, ds] = iir_butter(n, w, option, 's')
[as, bs, cs, ds] = iir_butter(n, [w1, w2], 'stop')
[as, bs, cs, ds] = iir_butter(n, [w1, w2], 'stop', 's')
Legacy Name: butter
Designs a Butterworth filter. If you specify w, this function generates a lowpass filter of order n. If you specify w1 and w2, this function generates a bandpass filter of order 2n. [z, p, k] and [as, bs, cs, ds] generate the zeropolegain representation and the statespace representation, respectively, of the filter.
Name  Description  

n  Specifies the filter order. n is a nonnegative integer.  
w  Specifies the cutoff frequency of the filter. w is a real number between 0 and 1. 1 represents the Nyquist frequency.  
w1  Specifies the low cutoff frequency. w1 must fall in the range [0, 1].  
w2  Specifies the high cutoff frequency. w2 must fall in the range [0, 1] and must be greater than w1.  
option  Specifies the type of filter to design. option is a string that accepts the following values.


'stop'  Directs LabVIEW to design a stopband filter. If you do not specify 'stop' and you specify w1 and w2, LabVIEW designs a bandpass filter.  
's'  Directs LabVIEW to design an analog Butterworth filter. 
Name  Description 

b  Returns the numerator of the filter under design. b is the forward filter coefficient of order n. b is a real vector. 
a  Returns the denominator of the filter under design. a is the backward filter coefficient of order n. a is a real vector. 
z  Returns the zeros of the filter. z is a vector. 
p  Returns the poles of the filter. p is a vector. 
k  Returns the gain of the filter. k is a real number. 
as  Returns the A coefficients of the filter. as is a matrix. 
bs  Returns the B coefficients of the filter. bs is a matrix. 
cs  Returns the C coefficients of the filter. cs is a matrix. 
ds  Returns the D coefficients of the filter. ds is a matrix. 
The following table lists the support characteristics of this function.
Supported in the LabVIEW RunTime Engine  Yes 
Supported on RT targets  Yes 
Suitable for bounded execution times on RT  Not characterized 
N = 5;
W = 0.4;
[B, A] = iir_butter(N, W)
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