Determine frequency of signals

Hi, how do I determine the frequency of this signal?

I got this from a .mat file

x = load('signal1.mat');

plot(x.x);

[KSSV]

Read about fft

Answer 1

[Chunru]

load signal1
fs = 1;         % normalized freq
y = abs(fft(x));
L = length(y);

f = (0:round(L/2)-1)/L*fs;
p = y(1:round(L/2));


[pmax, imax] = max(p);

plot(f, p, 'b-', f(imax), pmax, 'r*')

fprintf('The freq: %f\n', f(imax))

The freq: 0.012195