高手留步，MATLAB解DAE问题
解上图方程，以下是我的求解程序
k=1.1;
n=0.8;
odefun=@(t,x)[-n*pi*x(2)^2*x(4);%t对应theta，x(1)对应V，x（2）对应R，x（3）对应z，想（4）对应dz
-1/(tan(k*t))*x(4);
x(4);
x(1)*(sin(t))^3-pi/3*(x(2)^3)*((2-3*cos(t)+(cos(t))^3))];
tspan=;
x0=;
M=eye(4,4);
M(4,4)=0;
options=odeset('Mass',M);
=ode23t(odefun,tspan,x0,options);
但总是提示
Error using daeic12 (line 77)This DAE appears to be of index greater than 1.
Error in ode23t (line 289) = daeic12(odeFcn,odeArgs,t,ICtype,Mt,y,yp0,f0,...
Error in bingye (line 12)=ode23t(odefun,tspan,x0,options);
不会matlab，用mathematica做了下
t0 = 0.1; tend = Pi/2;
Manipulate[
{rsol, zsol, vsol} =
NDSolveValue[{r' == (-z')/Tan[ k t],
v' == n (Pi r^2 z'),
v/r^3 == (Pi/3) ((2 - 3 Cos + Cos^3)/Sin^3),
v == Pi/3, r == 1, z == 1}, {r, z, v}, {t, t0,
tend}] // Quiet;
Plot[{rsol, zsol, vsol}, {t, t0, tend},
AxesLabel -> Automatic, PlotTheme -> "Detailed",
PlotLegends -> "Expressions"], {k, 0.1, 1}, {n, 0.1, 1}]
页:
[1]