write a function doubleonleft that takes a vector and a numeric index as inputs, multiplies by 2, the value of the element on the left of that referenced by index, and returns the resulting vector. in matlab

main.m
function output = doubleonleft(vec, idx)
    if idx > 1
        vec(idx) = vec(idx) * 2 * vec(idx - 1);
    end
    output = vec;
end
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