Recent content by yangjun1222

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    How to understand negative frequency?

    Recently I learned some communication theory, which uses negative frequency, what does negative frequency means? So I checked textbook, found the negative frequency comes from the Fourier transform, which comes from the euler formula, e-jx=cosx+isinx, or another form cosx=(ejx+e-jx)/2, then any...
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    I am interested in physics, so hello every one here

    I am interested in physics, so hello every one here!