The plot shows the differences between a DFT and a DCT of a generic signal.
The first plot is a sampled ramp in the time domain. The second one represents the modulus of its DFT. The third one the plot of its DCT.
I obtained it in a two step process. First I ran the following Matlab code:




thus creating a file called example_dft_dct.dat. Then I ran the following Gnuplot code:
Own work
Alessio Damato