i need a psd library for getting the power of the spectrum of an EEG signal after having transformed it with FFT transform. Thank you!!

Why do you need to use a library? Once you have transformed using the FFT you just need to form (real**2 + imag**2) for each complex term of the FFT. Depending on the detail of your requirement you may then need to scale and combine the resulting terms.

Thank you very much!!

(real**2 + imag**2) is not the psd of the signal. It is the *magnitude*. Squaring the magnitude - i.e. (real**2 + imag**2)**2 - gives an *estimate* of the psd.
See this link for some info about psd.

Pete

The [u]magnitude[/u] of a complex number is sqrt(real^2 + imag^2).

OOOOooooopppss. My very bad. Thanks.

Pete