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These are replies submitted by AngieS7


One more question if it's okay. I have a similar case, with 6 equations and 6 unknowns, but the equations are a bit more lengthy and complicated. fsolve does not give the solution but just writes the equations again. what does this usually mean?

Thank you!

@dharr thank youuu!

@Carl Love

can you maybe help me with getting more solutions please? when I use 

omega_1 := 1;
beta_1 := 0.1;
omega_2 := 0.5;
beta_2 := 0.15;
mu := 0.4;
g := 9.81;
K := 0;
vb := 0.5;
tc := arccos(vb/(A*omega));

I get

sol := {A = 24.97595353, B = 0., C = 0., omega = -1.000000000, x1 = -7.898013362, x2 = 39.24000000}

The problem is that omega here, which is the oscillating frequency in my system is negative, so I am interested in other solutions. 

Thank you!

@Carl Love 

Thank you very much for your help! I get the same results now. Should be more careful with what I do. Thanks again!


Thank you very much! indeed, i had changed vb. I really appreciate your help!

@Carl Love 

Thank you very much for your help! I made the changes you suggested but still don't get a solution. After changing to 

sol := fsolve({eq1, eq2, eq3, eq4, eq5, eq6}, {A, B, C, omega, x1, x2})

I just get :

sol := fsolve({-5*x1 + 0.0225*x2 - 9.81, -omega^2*C + 0.0450*B*omega + 0.0225*C, x1 - 5*x2 - 1.99100*x2*(1 - 2*omega*arccos(5/(A*omega))/Pi) + 1.267509967*C*sin(omega*arccos(5/(A*omega))), 0.4*A*omega - 5*C + 2.535019933*x2*sin(omega*arccos(5/(A*omega))) + 0.6337549833*C*(2*omega*arccos(5/(A*omega)) + 2*sin(2*omega*arccos(5/(A*omega))) - Pi), -omega^2*A + A - 5*B + 0.6337549833*B*(2*omega*arccos(5/(A*omega)) - sin(2*omega*arccos(5/(A*omega))) - Pi), -omega^2*B - 0.0450*C*omega - 5*A + 0.0225*B}, {A, B, C, omega, x1, x2})

not sure if I'm doing smth else wrong, but its all the same other then the changes you suggested

@tomleslie thank you very much! setting the grid to [490,49] worked. 

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