I need to use the discrete fourier transform for function that represented as list of values. I started from the easy task to check am I use it right - try to reach the amplitude values fot 2*Sin[x] function. Looks like it should be somwhere about 2. But using the discrete 'Fourier' operation it is different. Can someone tell me - where is my mistakes? Please see my observations: data = Table[2*Sin[x], {x, 0, 100}]; ListPlot[data, Joined -> True] ![enter image description here][1] ListPlot[Abs[Fourier[data]], Joined -> True, PlotRange -> All] ![enter image description here][2] ListPlot[Table[ Abs[FourierTransform[2*Sin[x], x, w]] /. DiracDelta -> DiscreteDelta, {w, 0.1, 10, 0.1}], Joined -> True, PlotRange -> All] ![enter image description here][3] [1]: https://i.sstatic.net/YtAVI.jpg [2]: https://i.sstatic.net/ND47Q.jpg [3]: https://i.sstatic.net/0wyzX.jpg How can I reach fo the 'Fourier' operation the same results as I reach for the 'FourierTransform'? Thank you for help.