Read sunspot data s from file sunspot.dat, calculate the FFT of s, and graph the amplitudes and phases

 read sunspot.dat year s
 window 5
 set xlabel 'year'
 set ylabel 's'
 graph year s
 m = fft(s)
 window 6
 set ylabel 'amplitudes'
 graph m[*,2]
 window 7
 set ylabel 'phases'
 graph m[*,1]
 

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