temp = load('temp.dat');

Temp = temp(:, 1);
Time = temp(:, 2);

n = size(temp, 1);
I = abs(fft(Temp-mean(Temp))/sqrt(n));
P = I*4/n;
f = (0:176)./352;

plot(f, P(1:177), '-k', 'LineWidth', 2)

set(gca, 'Box', 'off', 'FontSize', 22, ...
         'XLim', [0, 0.5], 'YLim', [0, 0.048], ...
         'XTick', 0:0.1:0.5, 'YTick', 0:0.01:0.04, 'TickDir', 'out')

xlabel('Frequency', 'FontSize', 22)

set(gcf, 'Position', [200, 100, 1000, 800])