Error While Using the butter() function for IIR Butterworth filter design
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I am using Matlab 2012a. My code for the design of IIR Butterworth filter is:
clc
clear all
Fs=1000;
fc=300;
WC=2*pi*fc;
N=5;
[b,a]=butter(N,WC,'s');
[z,p,k]=butter(N,WC,'s');
[bz,az]=ipminvar(b,a,Fs);
[h, f]=freqz(bz,az,512,Fs);
plot(f, 20*log10(asb(h))),grid;
xlabel('frequency(Hz)');
ylabel('Magnitude(dB)');
The error encountered after execution of the program is:
??? Attempt to execute SCRIPT butter as a function: E:\Academics\6th Sem\DSP Lab\Exp-8\butter.m
Error in ==> butter at 8 [b,a]=butter(N,WC,'s');
Signal Processing Toolbox is already present in my Matlab. I have checked it using
>>ver
Please help me to debug the problem.
采纳的回答
Wayne King
2012-4-4
1 个投票
I don't see where you are using butter() at all in the code you have posted here. This is an FIR filter design. Did you copy and paste the wrong code?
At any rate, do not name a script, or variable the same name as an exisiting MathWorks' function. If you really have a script named butter.m on your path (E:\Academics\6th Sem\DSP Lab\Exp-8\butter.m) , then rename that to something like my_butter.m, anything but butter. Then enter
>>which butter
and make sure you get something like:
matlab\toolbox\signal\signal\butter.m
returned.
4 个评论
Arnab Ray
2012-4-4
Wayne King
2012-4-4
you spelled the function name incorrectly
impinvar
not ipminvar
Wayne King
2012-4-4
BTW, you have another spelling error: it's abs() not asb()
plot(f, 20*log10(abs(h))),grid;
Arnab Ray
2012-4-4
更多回答（1 个）
Honglei Chen
2012-4-4
0 个投票
This error
??? Attempt to execute SCRIPT butter as a function: E:\Academics\6th Sem\DSP Lab\Exp-8\butter.m
indicates that you have a butter.m on your path that shadowed MATLAB's butter() function. You need to either remove it from the path or change its name to something other than butter.
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