Vectors must be the same length

Hello, I've tryed few things but nothing is working can you help me, please ?

%% b
Xf=fft(x);
Ak=abs(Xf(n+1))/N;
T0=1/Fs;
w0=2*pi/T0;
Ts=1/1024;
Ak_t=fsAnalysis(x,t,T0,Ts,20);
figure;
plot(n(1:20)+1, Ak_t, 'b*'), axis([0 20 0 0.0005]);
xlabel('k'),ylabel('Ak_t(k)');
hold on;
plot(n(1:20)+1,Ak(1:20), 'r*');
legend('M. fft','M. trapezelor');
title ('FFT+ Trapeze');

ERROR

 'Error using plot
Vectors must be the same length.

Error in Lab13 (line 38)
plot(n(1:20)+1, Ak_t, 'b*'), axis([0 20 0 20]);'

Answer 1

[Sai Sri Pathuri]

Check whether n(1:20)+1 and Ak_t have same number of elements.

[Draghici Bogdan-Gabriel]

solved it, thanks