Help using solve function

Hello. I want to run the following code:

function [ema]=EMA(ec,fc,gamma,model)

if strcmp(model,'LL')==1

eh=1;

ema=solve((em-eh)/(em+gamma*eh)-sum(fc.*((ec-eh)./ec+gamma*eh))==0,em);

elseif strcmp(model,'MG')==1

eh=ec(fc==max(fc));

ema=solve((em-eh)/(em+gamma*eh)==sum(fc.*((ec-eh)./ec+gamma*eh)),em);

elseif strcmp(model,'B')==1

ema=solve(0==sum(fc.*((ec-em)./ec+gamma*em)),em);

end

I receive the following error:

Unrecognized function or variable 'em'.

I would think that solve assigns em as variable. I do not have the symbolic math toolbok yo use the function syms, which I have seen in some answers or documentation. Is there an alternative? I would guess so because solve does not require that toolbox.

If I try and replace the equation with a function handle as below I get the error

Operator '==' is not supported for operands of type 'function_handle'.

Thank you

fun=@(em) (em-eh)/(em+gamma*eh)-sum(fc.*((ec-eh)./ec+gamma*eh))
ema=solve(fun==0,em);

Answer 1

[David Hill]

fun=@(em) (em-eh)/(em+gamma*eh)-sum(fc.*((ec-eh)./ec+gamma*eh));
guess=5;%what is your best guess for what ema should be?
ema=fzero(fun,guess);