i have function L and initial values phi1 ,phi2 and seta . I want to be derivative this function and equal it by zero for getting the estimated values of these initial values. but showing the next error .what to do?

syms phi1 phi2 seta
L=- ((38*phi1)/281 - (89*phi2)/902 + (149*seta)/1124 - 83/28)^2/8; % function
phi1=0.3; % initial point
phi2=0.5; % initial point
seta=0.4; % initial point
phi1hat=fzero(L,phi1);
phi2hat=fzero(L,phi2); 
setahat=fzero(L,seta);
Error using fzero (line 167)
If FUN is a MATLAB object, it must have an feval method.

[KSSV]

Already you have defined phi1,phi2 and seta...what you want to find?

[mohammed elmenshawy]

A summary of what I want to do . i have function of 3 parameters L=f(phi1,phi2,seta). i need differential this function with respect to phi1 , phi2 and seta , and equality to zero. Hence we get three equations in three parameters , Give initial values of the three parameters.In the first equation, which is where the differentiation for phi1 we substitute only about phi2 and seta to get phi1 value . By this logic with the phi2 and seta . what to do ?

[John D'Errico]

Note that you were trying to solve a 3-dimensional problem, by calling fzero, a 1-d solver, three times. Sorry, but that makes no sense. Use fsolve preferentially, or lacking that, you can use fminsearch if used properly.