What's the wrong ?

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Lan
Lan 2015-3-11
回答： Jan 2015-3-11
the MATLAB program Matlab：edit， Then，the following lines between the percent sign (%) copied to m.file, save %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  function dx=myfun(t,x)
dx(1)-x(3)+x(2)-x(4)*x(2)+2*x(5)*x(2)+x(2)*x(2)+x(5)+e+f+g=0; 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=0; dx(3)-x(2)+x(1)-x(5)*x(1)+x(4)*x(3)-x(3)-x(4)-e*g-f=0; x(4)*x(5)+x(2)*x(3)+e*f+e*g-x(6)=0; dx(4)-x(5)*a-x(3)*x(1)-x(3)-e*f*g*x(6)=0; 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=0;
a=a1+a2; e=e1+e2; f=f1+f2; g=g1+g2;
a1=1; a2=1; e1=9; e2=7; f1=56; f2=98; g1=76; g2=665;
dx=dx(:); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
Matlab：  clear all clc syms a e f g a1 a2 e1 e2 f1 f2 g1 g2 x0=[1,1,1,1,1,1]; t0=0:0.1:2; [t,x]=solver('myfun',[0,10],x0);  %ode45会自动调整步长 plot(t,x)  legend('x(1)','x(2)','x(3)','x(4)','x(5)','x(6)')
  1 个评论
Jan
Jan 2015-3-11
编辑：Jan 2015-3-11
Please use a meaningful tag. If you explain, why you think, that there is something wrong, we do not have to guess this fundamental detail. Please avoid non-english comments, format your code properly in the forum and explain the problem with details. Thanks.
clear all removes all debugger breakpoints. But the debugger is the freidn of programmers. So start with deleting this cruel command, such that you can use the debugger to examine the code.

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回答（1 个）

Jan
Jan 2015-3-11
dx(1)-x(3)+x(2)-x(4)*x(2)+2*x(5)*x(2)+x(2)*x(2)+x(5)+e+f+g = 0;
This is a formula, but to assignment operation in Matlab. You should get an error message for this code. If so, please post it and look for examples for using ODE45.
syms a e f g a1 a2 e1 e2 f1 f2 g1 g2
You do not use these symbolic variables inside the function to be integrated. Defining them as symbolic outside this function is not meaningful.

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