solve() "Unable to find explicit solution"

Using solve for an equation is not working and I'm not sure why. This has an explicit solution but it doesn't work. What am I missing?

syms g m L s Y(s) 
solve(- m*(s - s^2*Y(s) + 1)*L^2 + g*m*Y(s)*L == 0,Y(s))

Warning: Unable to find explicit solution. For options, see help.

ans = struct with fields:
    m: [0×1 sym]
    s: [0×1 sym]

Answer 1

[Dyuman Joshi]

solve() expects the 2nd input to be an array of symbolic variable(s), where as you have defined Y as a symbolic function.

If you want to get the output as a function of "s", define it accordingly -

syms g m L s Z
Y(s) = solve(- m*(s - s^2*Z + 1)*L^2 + g*m*Z*L == 0,Z)

[Andrew]

Thanks! This was the problem.

Answer 2

[Sam Chak]

Hi @Andrew

If this is related to deriving the transfer function using Laplace transform, then I prefer using the isolate() function.

syms g m L s Y(s) 
Eqn = - m*(s - s^2*Y(s) + 1)*L^2 + g*m*Y(s)*L == 0;
Eqn = isolate(Eqn, Y(s))

Eqn = 

[Andrew]

Yeah it is related to the transfer function. This is very useful thanks for your help.

Answer 3

[Walter Roberson]

(I am absolutely positive I had already answered this, but there is no trace of that...)

solve() cannot solve for functions. You will need to substitute a symbolic variable for the function. For example,

syms g m L s Y(s) Ys
eqn = - m*(s - s^2*Y(s) + 1)*L^2 + g*m*Y(s)*L == 0;
solve( subs(eqn, Y(s), Ys), Ys)

ans = 

[Andrew]

Thanks! This was the problem.