Assuming it's not your homework (because you'd get into trouble for submitting our code as your own), try this:
x = linspace(1, 5, 500); % Only 5 elements if we step by 1 so use more to get a smooth curve.
numberOfSums = 10;
Lx = 10 % A scalar.
n = 1 : numberOfSums % 10 elements
omega = n .* pi / Lx % 10 elements
for k = 1 : numberOfSums
thisOmega = omega(k);
fprintf('Building curve #%d of %d with omega = %.4f...\n', k, numberOfSums, thisOmega);
thisCurve = sin(thisOmega .* x);
if k == 1
fx = thisCurve;
else
fprintf(' Summing in curve #%d of 10 to the master curve...\n', k);
fx = fx + thisCurve;
end
end
plot(x, fx, 'b-', 'LineWidth', 2);
grid on;
