# Relative Power using Matlab

1. Nov 4, 2009

### Kipster1203

I have the following code

dt = 0.01; % Set the time increment to 0.02 second.
t = (0:1:199)*dt; % Create a time array.
x1 = 0.5*square(pi*t); % Use MATLAB to create the signal
% amplitude +/- 0.5 and period 2.
subplot(2,1,1),plot(t,x1), axis([0,2.1,-0.6,0.6]);
x2 = zeros(1,length(x1)); % Define an empty column vector for the
% triangle function.
% Use a discrete approximation to the integral of the square
% wave to create the triangular signal.
x2(1) = -0.25;
for i = 2:200; x2(i) = x2(i-1) + x1(i)*dt; end
subplot(2,1,2),plot(t,x2), axis([0,2.1,-0.6,0.6]);

I need to calculate the sums of the power (by evaluating the fourier coefficients) in harmonics 1 - 3, 1 - 9, and 1 - 29 for signal x1 relative to the total power in the original signal x1.
Can anyone help me out??