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<HTML>
<HEAD>
<TITLE>Analyze data using FFT</TITLE>
</HEAD>
<BODY BGCOLOR="#FFFFFF" TEXT="#000000">
<P>
Read sunspot data s from file <a href="sunspot.dat">sunspot.dat</a>,
calculate the FFT of s, and graph the amplitudes and phases<br />
<P>
<font color="blue"><pre>
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]
</pre></font></P>
<P>
<img src="fft.gif"></p>
<P>
<a href="defineplotfunction.htm"><img src="../shadow_left.gif">
<font size="+1" color="olive">Define and plot a function</font></a><br />
<a href="contourdensity.htm"><img src="../shadow_right.gif">
<font size="+1" color="olive">Display array data as contours and density plot</font></a>
</P>
</BODY>
</HTML>
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