Unrecognized function or variable 't' for three dimensional structure

Hello all,

Somehow i am getting error for Unrecognized function or variable 't'. But i could not figure out why.

What is wrong in the code? As far as i see i have error in line i mention.

Vb1=0.5;                 %% Bariyer yüksekliği[eV]


WLt = 1.5e-9;
Rx = 5E-9;
Ry = 10E-9;        
Rz = 15E-9;           
x0=0;y0=0;z0=-WLt;    

alfa = 1E-9;
w=1E+12; T=2*pi/w;

for i=1:numel(z)
    for j=1:numel(y)
        for k=1:numel(x)
            fz = @(t) z(i) + alfa*sin(w.*t);
            idx_QD = @(t) ((x(k)-x0)/Rx).^2 + ((y(j)-y0)/Ry).^2 + ((fz(t)-z0)/Rz).^2 < 1 ;
            
            idx_QD(fz(t) < z0) = @(t) 0;       %%%%% ERROR IS FROM THIS LINE %%%%%%%%%%%                                        

            idx_WL = (fz(t) < 0) & (fz(t) > -WLt);  

            idx =@(t) idx_QD(t) | idx_WL(t);

            Vb =@(t) (idx(t))*0 + (1-idx(t))*Vb1 ;
            V0(i,k,k) = (1/T).*integral(Vb,0,T);
        end
    end
end

Answer 1

[Walter Roberson]

            idx_QD = @(t) (fz(t) >= z0).*(((x(k)-x0)/Rx).^2 + ((y(j)-y0)/Ry).^2 + ((fz(t)-z0)/Rz).^2 < 1);

idx_WL = @(t) (fz(t) < 0) & (fz(t) > -WLt);

[Özgür Alaydin]

Thanks working.