我想解决7个微分方程，它们是7个未知数的时间函数。 我想找到方程的解决方案：
eo(t)=f1(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
e1(t)=f2(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
e2(t)=f3(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
e3(t)=f4(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
w1(t)=f5(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
w2(t)=f6(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
w3(t)=f7(e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
我已经生成了e0, e1, e2, e3, w1, w2, w3的方程式。
现在，我该如何解决这些方程式，以及需要哪些命令？
我需要找到e0, e1, e2, e3, w1, w2, w3的值，并根据t获取这些值。
必须解决的方程是
e0 = - (e_1(t)*w_1(t))/2 - (e_2(t)*w_2(t))/2 - (e_3(t)*w_3(t))/2
e1 = (e_0(t)*w_1(t))/2 - (e_2(t)*w_3(t))/2 - (e_3(t)*w_2(t))/2
e2 =(e_0(t)*w_2(t))/2 - (e_1(t)*w_3(t))/2 + (e_3(t)*w_1(t))/2
e3 = (e_0(t)*w_3(t))/2 + (e_1(t)*w_2(t))/2 - (e_2(t)*w_1(t))/2
w1 = w_2(t)*(1.98019*e_3(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 1.980*e_0(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t)) - 1.980*e_1(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) - 1.9801*e_2(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t))) - 1.0*w_1(t)*(1.0*e_0(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 1.0*e_1(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t)) - 1.0*e_2(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) - 1.0*e_3(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t))) - 1.0*w_3(t)*(1.0*e_0(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) - 1.0*e_2(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 1.0*e_1(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t)) + 1.0*e_3(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t))) - (63.366*kappa^2*(0.72470*w_1(t) + 0.355*kappa*(2.0*e_0(t)e_1(t)(2.0*e_0(t)*e_3(t) + 2.0*e_1(t)*e_2(t)) + 2.0*e_1(t)e_3(t)(e_0(t)^2 - 1.0*e_1(t)^2 + e_2(t)^2 - 1.0*e_3(t)^2)) - 0.3623*kappa*((e_0(t)^2 + e_1(t)^2 - 1.0*e_2(t)^2 - 1.0*e_3(t)^2)*(e_0(t)^2 - 1.0*e_1(t)^2 + e_2(t)^2 - 1.0*e_3(t)^2) + (2.0*e_0(t)*e_3(t) + 2.0*e_1(t)e_2(t))(2.0*e_0(t)*e_3(t) - 2.0*e_1(t)*e_2(t)))))/(l^5*rho)
w2 = w_3(t)*(0.505*e_1(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) - 0.505*e_0(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t)) + 0.505*e_2(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t)) + 0.505*e_3(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t))) - 1.0*w_1(t)*(0.505*e_3(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 0.505*e_0(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t)) - 0.505*e_1(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) - 0.505*e_2(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t))) - 1.0*w_2(t)*(1.0*e_0(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 1.0*e_1(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t)) - 1.0*e_2(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) - 1.0*e_3(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t))) - (32.0*kappa^2*(0.7184*w_2(t) - 0.3592*kappa*(2.0*e_0(t)e_1(t)(e_0(t)^2 + e_1(t)^2 - 1.0*e_2(t)^2 - 1.0*e_3(t)^2) + 2.0*e_1(t)e_3(t)(2.0*e_0(t)*e_3(t) - 2.0*e_1(t)*e_2(t)))))/(l^5*rho)
w3 = w_1(t)*(1.0*e_2(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) - 1.0*e_0(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) + 1.0*e_1(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t)) + 1.0*e_3(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)w_2(t))) + w_2(t)(1.980*e_0(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t)) - 1.980*e_1(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 1.980*e_2(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t)) + 1.980*e_3(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t))) - 1.0*w_3(t)*(1.0*e_0(t)*(e_1(t)*w_1(t) + e_2(t)*w_2(t) + e_3(t)*w_3(t)) + 1.0*e_1(t)*(e_2(t)*w_3(t) - 1.0*e_0(t)*w_1(t) + e_3(t)*w_2(t)) - 1.0*e_2(t)*(e_0(t)*w_2(t) - 1.0*e_1(t)*w_3(t) + e_3(t)*w_1(t)) - 1.0*e_3(t)*(e_0(t)*w_3(t) + e_1(t)*w_2(t) - 1.0*e_2(t)*w_1(t))) + (63.366*kappa^2*(0.3551*kappa*((e_0(t)^2 + e_1(t)^2 - 1.0*e_2(t)^2 - 1.0*e_3(t)^2)*(e_0(t)^2 - 1.0*e_1(t)^2 + e_2(t)^2 - 1.0*e_3(t)^2) - 1.0*(2.0*e_0(t)*e_3(t) + 2.0*e_1(t)e_2(t))(2.0*e_0(t)*e_3(t) - 2.0*e_1(t)*e_2(t))) - 0.724*w_3(t) + 0.362*kappa*((e_0(t)^2 + e_1(t)^2 - 1.0*e_2(t)^2 - 1.0*e_3(t)^2)*(e_0(t)^2 - 1.0*e_1(t)^2 + e_2(t)^2 - 1.0*e_3(t)^2) + (2.0*e_0(t)*e_3(t) + 2.0*e_1(t)e_2(t))(2.0*e_0(t)*e_3(t) - 2.0*e_1(t)*e_2(t)))))/(l^5*rho)
在分配值
后，我在MATLAB中使用了这段代码soll=ode45(e0,e1,e2,e3,w1,w2,w3,e_0(t),e_1(t),e_2(t),e_3(t),w_1(t),w_2(t),w_3(t))
但是我收到以下错误消息：
未定义的功能＆＃39;存在＆＃39;对于输入参数类型为＆＃39; sym＆＃39;。
odearguments（第59行）中的错误if（exists（ode）== 2）
ode45中的错误（第113行）[neq，tspan，ntspan，next，t0，tfinal，tdir，y0，f0，odeArgs，odeFcn，...
请告诉我哪里出错了。
答案 0 :(得分：0)
此错误表示ode45无法解决符号方程（您的变量属于＆＃39; sym＆＃39;）。实际上ode45是一个数值解算器，它在函数上工作，而不是符号表达式。以下是define a function in Matlab：
首先，您需要创建一个新的m文件，然后键入此代码
function y = f(x)
y = 2 * (x^3) + 7 * (x^2) + x;
使用文件名保存＆＃39; f.m＆＃39;