what is IFFT (inverse FFT) equation. And how to derive it from FFT equation? Is FFT equation same as DFT equation which is X(k)= Σ x(n)e^(-j*2*pi*k*n/N) Σ is from k=0 to N-1 ???? and what is equation for IDFT and IFFT?
what is IFFT (inverse FFT) equation. And how to derive it from FFT equation?
Started by ●September 21, 2011
Reply by ●September 21, 20112011-09-21
mackenfy wrote:> what is IFFT (inverse FFT) equation. And how to derive it from FFT > equation? >=20 > Is FFT equation same as DFT equation which is X(k)=3D =CE=A3 > x(n)e^(-j*2*pi*k*n/N) > =CE=A3 is from k=3D0 to N-1 > ???? >=20 > and what is equation for IDFT and IFFT?
Reply by ●September 21, 20112011-09-21
On 21.9.11 7:52 , mackenfy wrote:> what is IFFT (inverse FFT) equation. And how to derive it from FFT > equation? > > Is FFT equation same as DFT equation which is X(k)= Σ > x(n)e^(-j*2*pi*k*n/N) > Σ is from k=0 to N-1 > ???? > > and what is equation for IDFT and IFFT?It seems that you need some basics: Google for 'Fourier series' and 'Fourier transform'. FFT is an efficient way of computing the discrete Fourier transform. The basic mathematics stay the same. -- Tauno Voipio
Reply by ●September 21, 20112011-09-21
> > >mackenfy wrote: > >> what is IFFT (inverse FFT) equation. And how to derive it from FFT >> equation? >>=20 >> Is FFT equation same as DFT equation which is X(k)=3D =CE=A3 >> x(n)e^(-j*2*pi*k*n/N) >> =CE=A3 is from k=3D0 to N-1 >> ???? >>=20 >> and what is equation for IDFT and IFFT? >What??????? And what is STUPIDENT????? you? if you don't help don't reply!
Reply by ●September 21, 20112011-09-21
mackenfy wrote:>> >>mackenfy wrote: >> >> >>>what is IFFT (inverse FFT) equation. And how to derive it from FFT >>>equation? >>>=20 >>>Is FFT equation same as DFT equation which is X(k)=3D =CE=A3 >>>x(n)e^(-j*2*pi*k*n/N) >>>=CE=A3 is from k=3D0 to N-1 >>>???? >>>=20 >>>and what is equation for IDFT and IFFT? >> > > What??????? > > And what is STUPIDENT????? you? > > if you don't help don't reply!
Reply by ●September 22, 20112011-09-22
On Sep 21, 1:13�pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:> mackenfy wrote: > > >>mackenfy wrote: > > >>>what is IFFT (inverse FFT) equation. And how to derive it from FFT > >>>equation? > >>>=20 > >>>Is FFT equation same as DFT equation which is X(k)=3D =CE=A3 > >>>x(n)e^(-j*2*pi*k*n/N) > >>>=CE=A3 is from k=3D0 to N-1 > >>>???? > >>>=20 > >>>and what is equation for IDFT and IFFT? > > > What??????? > > > And what is STUPIDENT????? you? > > > if you don't help don't reply!The Fast Fourier Transform (FFT) is merely a fast way of calculating the DFT (Discrete Fourier Transform). Given your original equation you want to solve for x(n). You can do this by using the orthogonal properties of the discrete exponential. Multiply both sides by an exponential and carry out a summation. Do to the orthogonality some of the summations in the starting equation will disappear. Cheers, David
Reply by ●October 2, 20112011-10-02
On Sep 22, 8:22=A0am, Dave <dspg...@netscape.net> wrote:> On Sep 21, 1:13=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote: > > > > > > > mackenfy wrote: > > > >>mackenfy wrote: > > > >>>what is IFFT (inverse FFT) equation. And how to derive it from FFT > > >>>equation? > > >>>=3D20 > > >>>Is FFT equation same as DFT equation which is X(k)=3D3D =3DCE=3DA3 > > >>>x(n)e^(-j*2*pi*k*n/N) > > >>>=3DCE=3DA3 is from k=3D3D0 to N-1 > > >>>???? > > >>>=3D20 > > >>>and what is equation for IDFT and IFFT? > > > > What??????? > > > > And what is STUPIDENT????? you? > > > > if you don't help don't reply! > > The Fast Fourier Transform (FFT) is merely a fast way of calculating > the DFT (Discrete Fourier Transform).Provided the sampling is uniform. Hope this helps. Greg
