Found error "Undefined function 'minus' for input arguments of type 'cell'. Error in @(x,y)1./deff-w(x,y) "

I tried the integral on w(x,y) equation and it shows the above error..Please help!

a=19.38e-6;

L=2*a;

Cr=3.45;

Cb=4.06;

Cs=1.994;

A=150.454e3;

B=0.0535;

C=12.53e-9;

d0=1e-6

sig=290e6;

t=2.4e-6;

Deff=((A*C)-B^2)/A

k=((Cr*t*sig)/a^2)+((Cb*12*Deff)/a^4) % stifness in pa

area=L*L;

v=0.23;

E=170e9; % young's modulus

Q=E/(1-v^2);

E0=8.854e-12;

K=k*area; % stiffness in N

d0=0:0.1e-6:1e-6 % air gap

Vpi=sqrt((8*(d0.*d0.*d0).*K)/(27.*E0.*area));

figure(1)

plot(d0,Vpi);

xlabel('Gap')

ylabel('V-pullin')

Vb=12;

v=0.23;

di=0.2e-6; % insulator thickness

Erm=11.68; %dielectric constant of polysilicon

Eri=8; % dielectric constant of insulator

Fs=(1-0.271*v)/(1-v)

deff =(t/Erm)+(di/Eri)+d0

Pext=0;

X1=(Cs*Fs*(Q*t/a^4))

X2=0

X3=(((Cr.*t.*sig)./(a.^2))+((Cb.*12.*Deff)./(a.^4))-((E0.*Vb.^2)./2.*a)).*((4.*a)./deff.^3)+((0.394).*(a.^0.25)./(deff.^2.25))

X4=-(Pext+((E0.*Vb.^2)./2.*a)).*((2.*a)./deff.^2)+((0.315).*(a.^0.25)./(deff.^1.25))

W0= roots([X1 X2 X3 X4])

for n=1:length(W0)

if((imag(W0(n)==0)))

W0=W0(n);

end

end

Vb= 0:5:50

P1=((E0.*Vb.^2)./2.*a).*(((2.*a)./d0.^2)+((.265.*((2.*a).^0.25))./(d0.^1.25)))

P2= ((E0.*Vb.^2)./2.*a).*((4.*a./d0.^3)+((0.33125.*((2.*a).^(0.25)))./d0.^2.25))

W=abs(W0);

W1=W(1:2:end,:)

W1(12,:)=[];

W2= W1.'

P3= P2.*W2;

Pelec = P1+P3

figure(2)

plot(Pelec,Vb);

xlabel('Electrostatic Pressure')

ylabel('Bias Voltage')

figure(3)

plot(Vb,W2);

xlabel('Bias Voltage')

ylabel('Center Deflection')

syms w(x,y)

c(1) = 1

c(2) = 0.6832

c(3) = 0.3105

syms x y

S = sum(c(1:3).*(((x^2+y^2)/a^2).^n-1),1,3)

symvar(S,2)

w(x,y) = W0.*(1-x.^2/a.^2).^2 .*(1-y.^2/a.^2).^2 .* S;

wu = w(x,y)

fun = @(x,y) 1./deff - w(x,y); %error

q = integral2(fun,0,L,0,1e-6);

Cdeform= E0.*q;

Cff= (0.385.*deff)./a + 1.06.*((1./L).*deff).^(0.75) + (0.53./a).*(1e-6.*deff).^(0.5)

Cap = Cdeform.*(1+Cff)

figure(4)

plot(Vb,Cap)

xlabel('Bias Voltage')

ylabel('Capacitance')