quiz8_solution

# quiz8_solution - %SUNSPOT A script that loads sunspot.dat...

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Unformatted text preview: %SUNSPOT - A script that loads sunspot.dat, an ascii file %with column 1 as years and column 2 as wolfer index, into a MATLAB array, plots wolfer index vs. year, takes the fft of the input data, %plots power vs. frequency, plots power vs. period, and prints the %sunspot period to the title of power vs. period plot. %File written by S.C. Tegler. Last modified 3/31/11. %--------------------------------------------------load sunspot.dat year = sunspot(:,1); wolfer = sunspot(:,2); figure(1); plot(year,wolfer); xlabel('Year'); ylabel('Wolfer Index'); title('Sunspot Data'); Y = fft(wolfer); N = length(Y); Y(1) = 0; Power = abs(Y).^2; tau = year(2) - year(1); dv = 1/N*tau; v = 0:dv:(N-1)*dv; %loads sunspot.dat into MATLAB array %creates year vector %creates wolfer index vector %plots wolfer index vs. year %computes fft %length of fft vector %sets first element of fft output to 0 %computes power of fft output %computes time sampling interval %computes frequency sampling interval %computes frequency vector figure(2); %plots power vs. frequency plot(v,Power); xlabel('Frequency (1/yr)'); ylabel('Power'); title('Sunspot Power Spectrum'); figure(3); %plots power vs. period period = v.^(-1); %period vector [ampmax,indexmax] = max(Power); %amp and index of max value in Power sunper = period(indexmax); %sunspot period plot(period,Power); %makes the plot title(['Sunspot Period is ' ,num2str(sunper,'%4.2f'), 'Yrs']); xlabel('Period (Years)'); ylabel('Power'); ...
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