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【m.file】ODE45_fun：

function dx=ODE45_fun(t,x)
a1=1;a2=1;e1=9;e2=7;f1=56;f2=98;g1=76;g2=665;
a=a1+a2;
e=e1+e2;
f=f1+f2;
g=g1+g2;
dx(1)=x(3)+x(2)-x(4)*x(2)+2*x(5)*x(2)+x(2)*x(2)+x(5)+e+f+g;
dx(2)=x(1)+x(3)-x(4)*x(2)+x(2)*x(2)+x(5)*x(5)+x(5)*x(2)+e*f+g;
dx(3)=x(2)+x(1)-x(5)*x(1)+x(4)*x(3)-x(3)-x(4)-e*g-f;
x(6)=x(4)*x(5)+x(2)*x(3)+e*f+e*g; % not dx(6)
dx(4)=x(5)*a-x(3)*x(1)-x(3)-e*f*g*x(6)
dx(5)=x(4)*a-x(2)*x(1)+e*f*x(1)+x(2)*x(2)*x(5)+x(2)*x(5)*x(5)+e*f+f*g
dx=[dx(1);dx(2);dx(3);dx(4);dx(5);dx(6)];
【m.file】DE45_main：

tspan=[0,10];
x0=[0;0.1;2;0;0.1;2];
[t,x]=ode45('ODE45_fun',tspan,x0);
data=[t,x];
save ODE45_data.txt data -ascii
subplot(2,3,1),plot(t,x(1))
subplot(2,3,2),plot(t,x(2))
subplot(2,3,3),plot(t,x(3))
subplot(2,3,4),plot(t,x(4))
subplot(2,3,5),plot(t,x(5))
subplot(2,3,6),plot(t,x(6))

>> ODE45_main

dx =

1.0e+010 *

0.0000 0.0000 -0.0000 -2.6146


dx =

1.0e+010 *

0.0000 0.0000 -0.0000 -2.6146 0.0000

??? Attempted to access dx(6); index out of bounds because numel(dx)=5.

Error in ==> ODE45_fun at 14
dx=[dx(1);dx(2);dx(3);dx(4);dx(5);dx(6)];
Error in ==> funfun\private\odearguments at 110
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ==> ode45 at 173
[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, ...

Error in ==> ODE45_main at 3
[t,x]=ode45('ODE45_fun',tspan,x0);
(edited 9 years ago)
Can x、y、z、Y、b and c be derived by constant letters by matlab？.jpg67.1KB

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