showing error like Attempt to reference field of non-structure array?/

hello this is my code to plot a simple graph for (d and E). but it is showing this error like this.i cant rectify this.

d=0:10:40;
r=0.5;
q1=2.65;
E0=8.85*10^-12;
E1=60;
b1 =(d./r).^(2/3);
E2=E1./b1;
E3= E2.(d+r).^2/(2*r.^2);
S=d./r;
u1=E0.*E2.^2./(2);
u= E0.*E1^.2.*(S+2/4);
a1=d.^2;
a2=1.5.*a1;
q=a2.*q1./(a2+a1);
u3=u./q;
e2=S./4;
e1=S./2;
V2=E1.*d.*e1;
c=E0.*e2./(d.^2.*e2.^2);
plot(d,u)

[Amit]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

Answer 1

[Amit]

d=0:10:40; 
r=0.5; 
q1=2.65; 
E0=8.85*10^-12; 
E1=60; 
b1 =(d./r).^(2/3); 
E2=E1./b1; 
E3= E2.*(d+r).^2/(2*r.^2); 
S=d./r; u1=E0.*E2.^2./(2); 
u= E0.*E1^.2.*(S+2/4);  % You forgot to put the multiplication '*' in your code.
a1=d.^2; 
a2=1.5.*a1; 
q=a2.*q1./(a2+a1); 
u3=u./q; 
e2=S./4; 
e1=S./2; 
V2=E1.*d.*e1; 
c=E0.*e2./(d.^2.*e2.^2); 
plot(d,u)