Error with butter function

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Olumide Adedeji
Olumide Adedeji 2021-4-2
编辑： Jan 2021-4-6
I have been having this problem for a while now on my matlab 2020b while using the butter function to create a bandpass filter for a continous waveform seismogram. My input is in accordance to what is in the documentation
I created a bandpass filter function first
function [ ts ] = bandpassfilt( ts, dt, high, low )
[n ,q] = size(ts);
tap = tukeywin(n, 0.1);
[b,a] = butter(1,[low, high].*(2*dt),'bandpass');
for i = 1:q
ts(:, i) = single(filtfilt(b,a,double(ts(:, i).*tap).*tap));
end
end
clc
clear
close all
Then created a script named "quick filt" to filter and plot
load trace
%samples and timing
sps = 250; %node sample rate
dt = 1/sps;
%data_samps = 60*60*250;
% body wave filter bandwidth ~0.5-2 Hz
P_low = .5;
P_high = 2;
dat_filt_Z_p = bandpassfilt(trace', dt, P_high, P_low);
%% quick plot
figure
subplot(2,1,1)
plot(trace)
title('Unfiltered')
subplot(2,1,2)
plot(dat_filt_Z_p)
title('Filtered')
It gives the error
Error using *
Inner matrix dimensions must agree.
Error in butter>buttnum (line 179)
b = real(b*(kern*den(:))/(kern*b(:)));
Error in butter (line 133)
num = buttnum(btype,n,Wn,Bw,analog,den);
Error in bandpassfilt (line 7)
[b,a] = butter(1,[low, high].*(2*dt),'bandpass');
Error in quick_filt (line 16)
dat_filt_Z_p = bandpassfilt(trace', dt, P_high, P_low);
I am also getting errors for using the lines of code given as example in the documentation
Input
low=0.5;
high=2;
dt=1/250;
[b,a] = butter(1,[low, high].*(2*dt));
Error
Index exceeds matrix dimensions.
Error in zp2ss (line 131)
a1 = t\[-den(2) -den(3); 1 0]*t;
Error in butter (line 97)
[a,b,c,d] = zp2ss(z,p,k);
  4 个评论
显示 2更早的评论
Mathieu NOE
Mathieu NOE 2021-4-6
Well, you probably should ask the technical support of the vendor....
DGM
DGM 2021-4-6
Is it possible that the function butter() has been overloaded?

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