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Question: Evaluating a sum

Question:Evaluating a sum

Oliveira 180 Maple
sum
July 16 2019
0


 

> 

pde1 := k*(diff(u(x, t), x, x)) = diff(u(x, t), t)

k*(diff(diff(u(x, t), x), x)) = diff(u(x, t), t)

 (1)
> 

iv1 := u(0, t) = 0, u(L, t) = 0, u(x, 0) = 2;

u(0, t) = 0, u(L, t) = 0, u(x, 0) = 2

 (2)
> 

pdsolve([pde1, iv1], u(x, t))

u(x, t) = Sum(-4*(-1+(-1)^(_Z4*csgn(1/L)))*sin(Pi*_Z4*x/L)*exp(-Pi^2*_Z4^2*k*t/L^2)/(Pi*_Z4), _Z4 = 1 .. infinity)

 (3)
> 

subs(`~`[_Z4] = n, %)

u(x, t) = Sum(-4*(-1+(-1)^(_Z4*csgn(1/L)))*sin(Pi*_Z4*x/L)*exp(-Pi^2*_Z4^2*k*t/L^2)/(Pi*_Z4), _Z4 = 1 .. infinity)

 (4)
> 

``

 
"I would like to replace the symbol _Z4~ with the letter n. I tried with the subs command, but I could not. Can anyone help"?"" ""


 

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