# NFourierTransform do not show all points, even change PlotPoints and Exclusions

Needs["FourierSeries"]


I try solve the numerical Fourier transform of this function:

E0[y_, a_] := -(1/54) E^((2 (1 - 3 a) Tanh[2 a y]^2)/(9 a))Cosh[2 a y]^(-6 - 4/(9 a))
(-10 + 9 (11 - 34 a) a + 3 (-5 + 2 a) (-1 + 6 a) Cosh[4 a y] + (-6 - 3 a + 54 a^2)
Cosh[8 a y] + Cosh[12 a y])


where this E0 have the plot:

Then I use the NFourierTransform with two diferent methods, Automatic and LocalAdaptive:

F0[w_, a_] := NFourierTransform[E0[y, a], y, w,
Method -> {Automatic, "SymbolicProcessing" -> False}]


In both cases the plot of this numerical Fourier tranform, F0, do not show all points, even if Exclusions -> None, PlotPoints -> 1000 were used, as can be see below:

Plot[F0[w, 0.05], {w, -10, 10}, PlotRange -> Full,
Exclusions -> None, PlotPoints -> 1000, Frame -> True, Axes -> False]


How to show the continuous points of these plots?

I am uncertain in what version of Mathematica NFourierTransform occurs, but FourierTransform works well in Mathematica 10.4 in Windows 64x.

F0[w_, a_] := FourierTransform[E0[y, a], y, w,
Method -> {Automatic, "SymbolicProcessing" -> False}]
Plot[F0[w, 0.05], {w, -10, 10}, PlotRange -> Full, Frame -> True, Axes -> False]


Note that Method is an undocumented option of FourierTransform

It may be that the function NFourierTransform produces results with a small imaginary part. If so, Chop the solution.

My thanks to J. M. for pointing out in a comment below that NFourierTransform is a component of the FourierSeries package. With the addition of

Needs["FourierSeries"]


it can be combined with Chop to yield the desired plot, above.

F0[w_, a_] := Chop@NFourierTransform[E0[y, a], y, w,
Method -> {Automatic, "SymbolicProcessing" -> False}]

• NFourierTransform[] comes from loading <<FourierSeries​. Mar 12, 2016 at 8:23
• The Needs["FourierSeries"] was already present in this question. Mar 12, 2016 at 12:07
• @bbgodfrey My Mathematica is v.10.0.0.0 working in a Windows 8 -64bits. In fact, the FourierTransform works well and faster fort this question, however, even that the Method -> {Automatic, "SymbolicProcessing" -> False} do not a valid option in this case. Mar 12, 2016 at 12:12
• @MelinaA.H Yes, I noticed that Mathematica flags Method as not a valid option but nonetheless accepts and uses it. This is not the first time I have seen such behavior. Perhaps, Method is an undocumented experimental option. By the way, Needs["FourierSeries"]` is not in your question. Mar 12, 2016 at 14:05