SCILAB ode:如何求解二阶ODE

Question

我来自MATLAB的ode45，正在尝试学习scilab中的ode。我遇到了一个异常，我不确定如何解决。

function der = f(t,x)
    wn3 = 2800 * %pi/30; //rad/s
    m = 868.1/32.174; //slugs
    k = m*wn3^2; //lbf/ft
    w = 4100 * %pi/30; //rad/s
    re_me = 4.09/32.174/12; //slug-ft
    F0 = w^2*re_me; //lbf

    der(1) = x(2);
    der(2) = -k*x(1) + F0*sin(w*t);
endfunction

x0 = [0; 0];
t = 0:0.1:5;
t0 = t(1);
x = ode(x0,t0,t,f);
plot(t,x(1,:));

我收到一条我不理解的错误消息：

lsoda--  at t (=r1), mxstep (=i1) steps   
needed before reaching tout
      where i1 is :        500                                                  
      where r1 is :   0.1027287737654D+01                                       
Excessive work done on this call (perhaps wrong jacobian type).
at line    35 of executed file C:\Users\ndomenico\Documents\Scilab\high_frequency_vibrator_amplitude_3d.sce

ode: lsoda exit with state -1.

谢谢!

Answer 1

你的颂歌特别生硬(k = 2319733)。对我来说，给出这么大的最后时间是没有意义的。您采用的时间步长(0.1)对驱动频率也非常大。如果您替换这行

t = 0:0.1:5

通过

t = linspace(0,0.1,1001)

例如，在0、0.1和1000个时间步长内请求t的近似解，您将得到以下输出：

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