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🤖 AI / ML

希尔伯特变换作为无限矩阵Hilbert transform as an infinite matrix

johndcook.com·2026-05-23 节选正文

文章将希尔伯特变换重新表述为无限矩阵运算,连接了其傅里叶级数表示与线性代数视角。具体推导表明:若函数f(x)的傅里叶系数为cₙ,则其希尔伯特变换的系数为(-i sgn(n))cₙ,其中sgn为符号函数。这一数学视角简化了信号处理中的卷积计算,尤其适用于非平稳信号分析。作者强调,矩阵形式为数值实现提供了新思路。

John

The previous post linked to a post I wrote a few years ago about the Hilbert transform and Fourier series. That post says that if the Fourier series of a function is

then the Fourier series of its Hilbert transform is

When I looked back at that post I thought about how if you thought of the Fourier coefficients as elements of an infinite vector then the Hilbert transform can be represented as multiplying by an infinite block matrix.

I rarely see infinite matrices except in older math books. Apparently they were more fashionable a few decades ago than they are now. I suppose the notation falls between two stools, too concrete for some tastes and not concrete enough for others. The former folks would prefer something like H and the latter would prefer the sum above.

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