Vectors mut be the same length.

I have the following code:

% Вектор абцис частотних функцій і кут:

lomega=logspace(-1,1);

pl=lomega*1i;

% Передатна функція:

Wl=k./(T2*T1*p.^2+T1*p+1);

% Модуль передатної функції і її логарифмічний вигляд:

Al=abs(Wl);

L=20*log10(Al);

%Перевод даних в градуси:

fil=angle(Wl);

fil_d=fil.*180./pi;

H=20*log10(fil_d);

figure(3);

subplot(2,1,1);

semilogx (lomega, L), grid on

title('ЛАЧХ');%ЛАЧХ;

xlabel('ω');

ylabel('A');

subplot(2,1,2);

semilogx (lomega, H), grid on

title('ЛФЧХ');%ЛФЧХ;

xlabel('ω');

ylabel('φ');

It only gives:

Error using semilogx

Vectors must be the same length.

Error in Lab3_var5 (line 63)

semilogx (lomega, L), grid on

How can I correct it? Thank you.

[Torsten]

lomega has length 50, but variables are missing so that we could tell the length of Wl. But from the error message, it's not 50.

[Dyuman Joshi]

There are many undefined variables in the code above.

The number of elements of the variables (or vectors) to be plotted, lomega and L, are not the same.

To correct the error, make sure both variables have the same number of elements.

[Image Analyst]

What is the size of lomega and H? Evidently they don't have the same number of elements. Do you know how to debug? Look in the workspace panel for the sizes of the variables.

Debugging in MATLAB | Doug's MATLAB Video Tutorials

Answer 1

[Sulaymon Eshkabilov]

Check what is the size of the transfer function W1 size at first and then the question becomes clear.

Since k, T1, T2 are not given in your code, just assuming them to be scalars, your code works ok:

lomega=logspace(-1,1); 
pl=lomega*1i;
% Assuming these values for k, T1, T2
k = 1;
T1 = 1;
T2 = 2;
p=pl;
% Передатна функція:
Wl=k./(T2*T1*p.^2+T1*p+1);
% Модуль передатної функції і її логарифмічний вигляд:
Al=abs(Wl);
L=20*log10(Al);
%Перевод даних в градуси:
fil=angle(Wl);
fil_d=fil.*180./pi;
H=20*log10(fil_d);
figure(3);
subplot(2,1,1);
semilogx(lomega, L), grid on
title('ЛАЧХ');%ЛАЧХ;
xlabel('ω');
ylabel('A'); 
subplot(2,1,2);
semilogx(lomega, H), grid on

Warning: Imaginary parts of complex X and/or Y arguments ignored.

title('ЛФЧХ');%ЛФЧХ;
xlabel('ω');
ylabel('φ');

[Alisa-Oleksandra Kotliarova]

Thanks, that helped a lot!

[Sulaymon Eshkabilov]

Most welcome! Glad to help.