MathGroup Archive 1995

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Fourier Question


> I have a question concerning the Mathematica command 'Fourier'
...
> According to references, Exp[I 2 Pi f0/N x] Should cause a shift of f0,
> but does not.  Below are the commands I used in my trial.
> 
> g=UnitStep[x+5]-UnitStep[x-5];
> b= ;
> f1=Table[N[g*Exp[I x b]],{x,-63,64}];
> f2=Fourier[f1];
> ListPlot[Abs[f2]];

Just one minor problem here: in the phase factor Exp[I 2 Pi f0/N x],
x should be in the range {0, 127}:

b = 0;
f1=Table[N[g*Exp[I (x+63) b]],{x,-63,64}];
f2=Fourier[f1];

shift = 7;
b = shift 2Pi/128;
f1=Table[N[g*Exp[I (x+63) b]],{x,-63,64}];
f3=Fourier[f1];
f2 - RotateRight[f3, shift] // Chop

Eberhard Lange


  • Prev by Date: MathLink documentation
  • Next by Date: Re: projected gradient
  • Previous by thread: Re: Fourier Question
  • Next by thread: Re: Crossreference, code documentation