I want to plot (x vs t ) of a differential equation containing signum function.please help ASAP

 X" + x + signum(x') =0  

Answer 1

[Sam Chak]

Hi @RAJAT

You can find examples of solving ordinary differential equations in this link:

https://www.mathworks.com/help/matlab/ref/ode.html

F              = ode;                           % ODE object
F.InitialValue = [2; 0];                        % initial values
F.ODEFcn       = @(t, x) [x(2);                 % x1'
                        - sign(x(2)) - x(1)];   % x2'
F.SelectedSolver

ans = 
  SolverID enumeration

    ode45

S = solve(F, 0, 10);                            % Solve the ODE from 0 to 10 sec

% plot(S.Time, S.Solution(1,:), "-o"), grid on  % plot x1 vs t only
plot(S.Time, S.Solution, "-o"), grid on         % plot x1 and x2
xlabel('t'), ylabel('\bf{x}(t)')
legend("x_1", "x_2", Location="northeast")