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

조회 수: 5 (최근 30일)
SAHIL SAHOO
SAHIL SAHOO 2022년 8월 2일
댓글: Torsten 2022년 8월 2일
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);
  댓글 수: 1
Torsten
Torsten 2022년 8월 2일
Your equations cannot be solved using "dsolve" because they are far too compliciated.
Either use Walter's suggestion to prepare the function used for ODE45 by MATLAB's "odefunction"
or define your function to be used for ODE45 directly.

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