Warning: The number of equations exceeds the number of indeterminates. Trying heuristics to reduce to square system.

here is my code:

     %enter code here
     vo=550;
     Lk=1e-3;
     C=3e-9;
     c=3e-9;
     syms  vc1(t) vc2(t) il(t) ic1(t)
     equ1 = vc1 + vc2 - vo == 0;
     equ2= Lk * diff(il , t)- vc1 == 0;
     equ3 = ic1 == c * diff ( vc1 , t );
     equ4 = il +ic1 ==c *diff (vc2 , t );
     cond = [vc1(0) == vo , vc2(0) == 0, il(0)==0, ic1(0) == 0];
     [svc1(t), svc2(t) ] = dsolve ([equ1 , equ2 , equ3 , equ4 ], cond )

I am getting this repeated error.

Thanking in anticipation.

[Walter Roberson]

There is a solution,

ic1(t) = -(1/2)*c^(1/2)*2^(1/2)*sin((1/2)*2^(1/2)*t/(Lk^(1/2)*c^(1/2)))*vo/Lk^(1/2)
il(t) = c^(1/2)*2^(1/2)*sin((1/2)*2^(1/2)*t/(Lk^(1/2)*c^(1/2)))*vo/Lk^(1/2)
vc1(t) = vo*cos((1/2)*2^(1/2)*t/(Lk^(1/2)*c^(1/2)))
vc2(t) = -vo*(cos((1/2)*2^(1/2)*t/(Lk^(1/2)*c^(1/2)))-1)

[Archit Asthana]

What are the changes you made to the code.

[Walter Roberson]

I reformatted your code but did not change it.

I did not use your code to find a solution.

[Archit Asthana]

Can you please post your code Thanks in advance.

[Walter Roberson]

equ1 := vc1(t)+vc2(t)-vo = 0;
equ2 := Lk*(diff(il(t), t))-vc1(t) = 0;
equ3 := ic1(t) = c*(diff(vc1(t), t));
equ4 := il(t)+ic1(t) = c*(diff(vc2(t), t));
sol := dsolve({equ1, equ2, equ3, equ4});
eval(sol[1], t=0);
# we see that ic1(0) = sqrt(c) * sqrt(2) * _C1 / (2*sqrt(Lk)) and since we know that ic1(0) must be 0, by inspection _C1 must be 0
sol2 := eval(sol, _C1=0);
eval(sol2[3], t=0);
# we see that vc1(0) = _C2 and since we know that vc1(0) must be vo, by inspection _C2 must be vo

solution := eval(sol, [_C1=0, _C2=vo]);

crosscheck := eval(solution, t=0);
# yes, all of the boundary conditions are satisfied

[madhan ravi]

It happened to me once but when I didn’t use the intial co diction it worked . Try doing it or check the initial condition.

[Walter Roberson]

Yes, when I was working it through on Maple, Maple could not find the solution when I gave the initial conditions. I had to ask for the general solution and then use my knowledge of the initial conditions to pin down the values of the constants of integration.