May I know what the " normalized data " mean?
the 2nd graph is only a very small part of graph 1, where its kx is from 0 to 0.05 only. This is the relative k vector. In graph 1, the k is actually the sweep points of totaling 30 (each direction 10 points).
In both graphs the frequency is normalized with periodicity. Please check the script how the vertical axis is normalized. Fig 1 shows f_plot=f_actual*a/c and graph 2 should be the same although it does not mention.
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