Calculation of Fourier Amplitude Spectrum by Fast Fourier transform.

Keyword

Fourier Amplitude Spectrum,Fast Fourier transform,complex numbers,real number,Imaginary number.

Reference

[1]:『JavaScriptで学ぶ数値計算』(吉川浩).

Remarks

・Sample data:y=100*sin(2*π*0.25*t) + 50*cos(2*π*2*t) + 125*sin(2*π*1*t).n=128.Δt=0.03125(s).
・Amplitude
=((Real Number^2+Imaginary Number^2)^0.5)*2 :(Frequency>0Hz)
=((Real Number^2+Imaginary Number^2)^0.5) :(Frequency=0Hz)

History

・2009/10/10：BugFix
・2009/10/08：Upload.