My function doesn't append to it's list

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Kacper 2024-5-10

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评论： Kacper 2024-5-12

%calculates polynomials of form Pk = ((2k-1)t/k)*Pk-1 - ((k-1)/k)*Pk-2
function [poly, filllist] = calc_poly (n, t, filllist)
    if n == 0
        filllist = [filllist; ones(size(t))];
        poly = ones(size(t));
        return
    end
    if n == 1
        filllist = [filllist; t];
        poly = t;
        return
    end
    poly = ((2*n-1)/n)*t.*calc_poly(n-1, t, filllist) - ((n-1)/n)*calc_poly(n-2, t, filllist);
    filllist = [filllist; poly];
end

This function is supposed to recursively calculate the polys and append them into filllist, but the array remians unalatered after running it. I know that as it stands there would be duplicates in the list, but I first want to get the function to actually do anything.

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回答（1 个）

Steven Lord 2024-5-10

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Your recursive calls only call your function with one output argument, so the modified second output argument is not returned from that function. Therefore any changes you make to your third input argument are discarded when each recursive call returns.

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Walter Roberson 2024-5-12

Experiment with creating a script that has both parts together, and running the script. You can use the "Copy" box on the code I posted to get the code to be pasted into the script.

Kacper 2024-5-12