       Table to calculate faster

• To: mathgroup at smc.vnet.net
• Subject: [mg122354] Table to calculate faster
• From: Michelle Maul <michellemaul312 at gmail.com>
• Date: Wed, 26 Oct 2011 17:38:47 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```I am trying to perform a heat transfer calculation on a wall with
transient heating.  I am using rules so that we can easily change the
material.  I want to be able to do several hundred time steps but I am
only able to get about 10 in an hour.  It is a pretty straight forward
calculation so I'm wondering why it is taking so long to compute.
This is a calculation that Excel would be good at because it is taking
data from the cells above it to solve.  Help please

T[0, t_] := (1. -
2. \[Tau] - (2. \[Tau] Subscript[h, in] \[CapitalDelta]x)/k) T[
0, t - 1] +
2. \[Tau] T[1,
t - 1] + (2. \[Tau] Subscript[h, in] \[CapitalDelta]x)/k*
Subscript[T, in] /. masonry;

T[m_, t_] := \[Tau] (T[m - 1, t - 1] + T[m + 1, t - 1]) + (1. -
2. \[Tau]) T[m, t - 1] /. masonry;

T[5, t_] := (1. - 2. \[Tau] -
2. \[Tau] (Subscript[h, out] \[CapitalDelta]x)/k) T[5,
t - 1] + 2. \[Tau] T[4, t - 1] +
2. \[Tau] (Subscript[h, out] \[CapitalDelta]x)/
k*(Subscript[T, out] /. {x -> t}) +
2. \[Tau] (\[Kappa] *(Subscript[q,
solar] /. {x -> t}) \[CapitalDelta]x)/k /. masonry;

solution = Transpose[Table[T[n, x], {n, 0, 5}, {x, 0, 24}]]

Thank you

```

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