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]
Define and plot a function
Display array data as contours and density plot