Error using * Inner matrix dimensions must agree.

Can someone hepl me with this? I get an error at line 12.

function L=dispersion(T,d)
T=[0.5 0.5 2 2 8 10 14];
d=[0.1 0.5 0.1 0.5 10 50 0.5];
L=9.81*T.^2/(2*pi);
tol=10^-8;
err=tol+1;
while  err>=tol
   fL=L-((9.81*T.^2/(2*pi))*tanh(2*pi*d/L));
   fderL=1-(9.81*T.^2*d.*(tanh((2*pi*d)/L)^.2-1))/(L.^2);
   Lnew=L-fL/fderL;
   err=abs(L-Lnew);
   L=Lnew;
end

[Anusha Sridharan]

[Answers Dev] Restored edits

Answer 1

[KALYAN ACHARJYA]

fderL=1-(9.81*T.^(2*d.*(tanh((2*pi*d)/L).^2-1))/(L.^2));