temp = load('temp.dat');

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

co = cos(2*pi*Time/72);
si = sin(2*pi*Time/72);

lm_temp = regress(Temp, [ones(size(co)), co, si]);

plot(Time, Temp, '-k', 'LineWidth', 2)
hold on;
plot(Time, [ones(size(co)), co, si]*lm_temp, '-b', 'LineWidth', 2)

set(gca, 'Box', 'off', 'FontSize', 22, ...
         'XLim', [0, 360], 'YLim', [36.6, 38.4], ...
         'XTick', 0:72:288, 'YTick', 36.5:0.5:38.5, ...
         'XTickLabel', 0:4, 'TickDir', 'out')

cS = strcat('Temperature (', char(176), 'C)');
xlabel('Time (days)', 'FontSize', 22)
ylabel(cS, 'FontSize', 22)

set(gcf, 'Position', [200, 100, 1400, 600])