### Discrete Fourier transform

Calculates discrete FFT/IFFT of continuously and evenly-spaced data points. Result is normalized so that both direct and inverse transforms are scaled by $$1/\sqrt{N}$$, where $$N$$ is the number of data points.

Complex numbers can be provided as real and imaginary parts in separate columns, respectively, or in a single column, using j or i to indicate the imaginary unit (for example, 1+2j or 1+2*i)

Output is always in three columns: frequency, real value, imaginary value.