Symbolic toolbox help using solve command

I have the following simple code and Im not sure how else to solve it for more than one equation, the variable hl and hr can change at any time so I want matlab to automatically solve for the different equation im assuming its something simple that i have missed, thanks in advance kyle

hl = 1;
hr = 0.1;
g=9.81;

syms s
geneqn = s*((s - ((g*hr)/(4*s))*(1+(sqrt(1+((8*s^2)/(g*hr)))))) + 2*(sqrt(((g*hr)/2)*(sqrt(1+((8*s^2)/(g*hr)))-1))) - 2*sqrt(g*hl));

S = solve('geneqn=0') 

s=0 << %I know that this is not correct

Answer 1

[Andrei Bobrov]

hl = 1; hr = 0.1; g=9.81;
syms s
geneqn = s*((s - ((g*hr)/(4*s))*(1+(sqrt(1+((8*s^2)/(g*hr))))))...
      + 2*(sqrt(((g*hr)/2)*(sqrt(1+((8*s^2)/(g*hr)))-1))) - 2*sqrt(g*hl));
out = solve(geneqn,s)

on my PC:

[kyle lyth]

thank you for the quick response, i didn't realise it would solve for zero automatically :) thanks again kyle