Example 11.1-2 Heating of a Finite Slab: Part b using eq. 11.1-31

>  restart;
>  Thetan := (tau,eta,n)->exp(-(n+1/2)^2*Pi^2*tau)*
cos((n+1/2)*Pi*eta); The same function found in our last session.  
>  D1[n]:=4*(-1)^n/(2*n+1)/Pi;
>  Theta:=(tau,eta,N)->sum(D1[n]*Thetan(tau,eta,n),n=0..N);  
calculate Theta as in eq. 11.1-31, but the sum only includes a 
finite number of terms.
>  1-Theta(0.6,0.2,10); This is what is shown in Fig. 11.1-1
>  eq := (T1-T)/(T1-T0)=Theta(0.2,0.6,10);  This is the way 
eq. 11.1-31 reads.
>  T0:=100; T1:=250;
>  solve(eq,T);  solve for T