Unable To Convert Expression Into Double Array

Need get each 'Ef' value when 'Na' & 'Nd' changes. Can teach me how to solve the 'Ef' values.

problem resolved

Answer 1

[madhan ravi]

 E_f = cell(size(Na));
 for k = 1:numel(Na)
     ef = solve(Nc*exp((Ef-Ec)/(k*T))+Na(k)./(1+4*exp((Ea-Ef)/(k*T)))==Nv*exp((Ev-Ef)/(k*T))+Nd(k)./(1+2*exp((Ef-Ed)/(k*T))), 'maxdegree', 4);
     E_f{k}=double(ef);
 end
 celldisp(E_f)

[ZHAO YANG]

Bro, It's work