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Why won't this ODE setup work?

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AUSTIN WHITELEY
AUSTIN WHITELEY 2022-2-9
评论： Jan 2022-2-9
I'm trying to solve a system of differential equations with initial conditions in order to run simulations over time. Here is my code.
k1=23.18*10^3;
k2=192.7;
k_1=357.4;
k_2=.03;
syms cs(t) ces(t) cp(t) ce(t)%solving diff eq
eqs=diff(cs) == (-k1*ce*cs)+(k_1*ces);
eqces=diff(ces) == ((-k_1-k2)*ces)+(k1*ce*cs)+(k_2*ce*cp);
eqcp=diff(cp) == (-k_2*ce*cp)+(k2*ce*cp);
eqce=diff(ce) == (-k1*ce*cs)-(k_2*ce*cp)+((k_1+k2)*ces);
odes=[eqce; eqs; eqces; eqcp]
cond1 = ce(0) == (5*10^(-8));
cond2 = cs(0) == .004;
cond3= ces(0) == 0;
cond4= cp(0) == 0;
conds=[cond1; cond2; cond3; cond4];
[ceSol(t), csSol(t), cesSol(t), cpSol(t)]= dsolve(odes,conds);%I get an error on this line that says invalid indexing or function definition
ceSol(t)= simplify(ceSol(t));
csSol(t)= simplify (csSol(t));
cesSol(t)= simplify (cesSol(t));
cpSol(t)= simplify (cpSol(t));
Any idea where I'm going wrong?

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回答（1 个）

Jan
Jan 2022-2-9
Omit the "(t)" in the output:
[ceSol, csSol, cesSol, cpSol]= dsolve(odes,conds);
  2 个评论
AUSTIN WHITELEY
AUSTIN WHITELEY 2022-2-9
After making that change it returns [ceSol, csSol, cesSol, cpSol] as empty variables. Is there anything else I need to do?
Jan
Jan 2022-2-9
When I run the code, I get the warning: "Unable to find symbolic solution". Most ODEs do not have a symbolic solution, but you have to solve them numerically. Do you have any reason to assume, that there is a symbolic solution of your equation?

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