The only transform which we may calculate using our PC or any other machine isDFT
All the other transforms are theoretical
Because the Limits are from -Inf to +Inf
Where as the limits in DFT are real Numbers so we calculate only DFT, Practically.
FFT is nothing but a Optimized technique for calculation of DFT, So its the same thing
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And Also Because the transform other than DFT have limits of Continuous Variables
And the Limits of DFT are Discrete Nimbers