Hi @Maria
Please check your second state equation. It does not produce a circle in the phase portrait. However, I will show you an example that produces a perfect circular trajectory.
M8
function M8
n = 0; b = 0; k = 1; a = 1; h = 0; p = 1; x = 2;
f = @(t, y) [y(2);
- y(1)];
% f = @(t, y) [y(2);
% y(2) + 2*n*(1 + a*y(1)^3)*y(1) + k^2*(y(1) + b*y(1)^3) - h*sin(p*x)];
% disp('Значения параметров: n = 0,b=0, k = 1, a = 1, h = 0, p = 1')
% disp('Решение задачи Коши для уравнения')
tspan = [0, 100]; %
y0 = [0, 1]; % initial values: y1(0) = 0, y2(0) = 1
[t, y] = ode45(f, tspan, y0);
% disp(z);
% tic, [~,y] = ode45(f,[0,1],[0,0]);toc
plot(y(:,1), y(:,2))
grid on
axis equal
xlabel y_1
ylabel y_2
end
