Vectors must be the same length
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Hello,
Although my code is at a beginner's level (see below), I can't get rid of the error you see in the attached photo.
I haven't really understood the problem, so I can't find a way to correct the length of these vectors.
Maybe there's an easier way to write my code.
Thanks for helping me out ;)
% --------------
% | EXERCISE 3 | - RLC Circuit
% --------------
% DE useful to describe the behaviour of the
% RLC Circuit's components over time
%********************************************************
% Non-homogeneous equation
% | ay''(t) + by'(t)+cy(t) = u(t) |
% Kirchhoff's voltage law in RLC Circuits
% | Lq''(t) + Rq'(t) + 1/Cq(t) = u(t) |
% with L Inductance (Henry H)
% R resistor's resistance (ohms)
% C capacitor's capacitance (Farads F)
% q(t) capacitor's charge at a time t (Coulombs C)
% i(t) current through the circuit at time t (Amperes A)
% u(t) applied voltage (Volts V)
% Remove all variables and functions from the memory
clear;
close all;
disp('start');
% Given parameters
R = 1;
L = 0.2;
C = 0.5;
U = 1;
T = 3; % Time span
% Initial conditions
q0 = 0; % Initial capacitor's charge
q_dot_0 = 0; % Initial charge's derivative, = current
% Time span for plotting
tspan = linspace(0, T, 100);
% Solve the DE with ODE45
[t, q] = ode45(@(t, q) (U - (R * q) / L - q / (L * C)), tspan, [q0, q_dot_0]);
% Calculate current and voltages
i = diff(q(:, 1)) ./ diff(t); % Current derivative
U_R = R * i; % Resistor's voltage
U_L = L * diff(i); % Coil's voltage
U_C = q(:, 1) / C; % Capacitor's voltage
% Plot Graph
figure;
plot(t, U_R, 'LineWidth', 1.5);
hold on;
plot(t, U_L, 'LineWidth', 1.5);
plot(t, U_C, 'LineWidth', 1.5); % Remove the initial value to match lengths
hold off;
titleText = sprintf('Evolution of the voltage in the components of a RLC-circuit (R = %.2f, L = %.2f, C = %.2f, U = %.2f)', R, L, C, U);
title(titleText);
xlabel('Time t');
ylabel('Voltage (V)');
legend({'U_R', 'U_L', 'U_C'}, 'FontSize', 12);
grid on;
disp('done');
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