using "for loop" to solve 5 different coupled differential equation.

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SAHIL SAHOO 2022-8-2

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https://ww2.mathworks.cn/matlabcentral/answers/1772375-using-for-loop-to-solve-5-different-coupled-differential-equation

评论： Torsten 2022-8-2

syms A(t) O(t)
a = 0.6;
n = 0.05;
tc = 10E-9;
r = 1.5;
F = 1;
N = 5;
for i = 1:N
ode1 = diff(A(i)) == (-1/(2*tc)).*(1 - r/(1+ (A(i)^2)./F)).*A(i) + (n/(2*tc)).*((cos(O(i))).*A(i+1) + (cos(O(i-1))).*A(i-1)) ;
ode2 = diff(O(i)) ==  (a./(2*tc)).*(  r/(1 + (A(i+1)^2)./F) - r/(1 + (A(i)^2)./F) ) + (n/(2*tc)).*(((A(i+2)./A(i+1)).*sin(O(i+1))) - (A(i+1)./A(i) + A(i)./A(i+1) ).*sin(O(i)) + (A(i-1)./A(i)).*sin(O(i-1)));
odes = [ode1(i); ode2(i)]
S(i) = dsolve(odes(i))
A(i)Sol(t) = S.A(i)
Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.
O(i)Sol(t) = S.O(i)
[A(i)Sol(t),O(i)Sol(t)] = dsolve(odes(i))
conds = [1; 0];
[A(i)Sol(t),O(i)Sol(t)] = dsolve(odes(i),conds)
fplot(A(i)Sol)
hold on
fplot(O(i)Sol)
grid on
end

I want to use for loop so it will solve 5 couple differential equation,

first it will take i =1 to solve A(1) and O(1) and then i want to plot A(1) vs time. i want to do this till A(5).

and i want to put a condition in which is like if i >=5 then the i+1 becomes 1 and i+2 becomes 2.

odes =

Error using mupadengine/feval_internal
No differential equations found. Specify differential equations by using symbolic functions.

Error in dsolve>mupadDsolve (line 334)
T = feval_internal(symengine,'symobj::dsolve',sys,x,options);

Error in dsolve (line 203)
sol = mupadDsolve(args, options);