Error on filter() - Subscript indices must either be positive integers or logicals

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Bryan Wilson 2017-12-14

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https://ww2.mathworks.cn/matlabcentral/answers/372846-error-on-filter-subscript-indices-must-either-be-positive-integers-or-logicals

评论： Jan 2017-12-14

I'm trying to use filter() to do a moving average on my data, but I keep getting the error "Subscript indices must either be positive integers or logicals." What's really bothering me is I get the same error when I try running the example on the filter() webpage. Here's the example. It breaks on the y=filter(b,a,x) line.

    t = linspace(-pi,pi,100);
    rng default  %initialize random number generator
    x = sin(t) + 0.25*rand(size(t));
    windowSize = 5; 
    b = (1/windowSize)*ones(1,windowSize);
    b = [1/5 1/5 1/5 1/5 1/5]
    a = 1;
    y = filter(b,a,x);
    plot(t,x)
    hold on
    plot(t,y)
    legend('Input Data','Filtered Data')

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Walter Roberson 2017-12-14

在 MATLAB Online 中打开

What shows up for

which -all filter

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Answer 1

Jan 2017-12-14

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https://ww2.mathworks.cn/matlabcentral/answers/372846-error-on-filter-subscript-indices-must-either-be-positive-integers-or-logicals#answer_296217

在 MATLAB Online 中打开

Hi Brian, did you see Walter's comment? Most likely the symbol "filter" was overwritten by a variable. Then the builtin function is "shadowed". If this is your problem:

clear filter

and do not use the name of builtin functions for variables in general.