IFFT on padded vector with zeros

Question

Michael Adelman 2013-2-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/64444-ifft-on-padded-vector-with-zeros

hello,

I have a vector that padded with zeros and I want to perform IFFT on this vector, as follows: [ 1 2 3 4 0 0 0 . . . 0 0 4 3 2 1] In that case, do I need to multiply IFFT with scaling factor?

Thanks,

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Matt J 2013-2-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/64444-ifft-on-padded-vector-with-zeros#answer_76024

编辑：Matt J 2013-2-21

在 MATLAB Online 中打开

You might have to scale by a length-dependent factor, depending on what it is you're trying to preserve. For example, if you want to satisfy Parseval's theorem, you have to scale by sqrt(length(x)),

    >> x1=[ 1 2 3 4  4 3 2 1];
    >> x2=[ 1 2 3 4 0 0 0 0  4 3 2 1];
    >> 
    >> y1=ifft(x1)*sqrt(length(x1));
    >> y2=ifft(x2)*sqrt(length(x2));
    >> [norm(x1), norm(y1)]   %Parseval satisfied
    ans =
        7.7460    7.7460
    >> [norm(x2), norm(y2)] %Parseval satisfied
    ans =
        7.7460    7.7460