Re: Table to calculate faster

*To*: mathgroup at smc.vnet.net*Subject*: [mg122440] Re: Table to calculate faster*From*: Oliver Ruebenkoenig <ruebenko at wolfram.com>*Date*: Fri, 28 Oct 2011 05:37:33 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201110271032.GAA08914@smc.vnet.net>

Also, masonry is missing. Some ideas could be to use T[..]:=T[..]=Evaluate[....] or some such combination. It is really better to send examples that actually have working code. Another approach could be to use linear algebra A.T=b Oliver On Thu, 27 Oct 2011, Jacopo Bertolotti wrote: > Maybe it's just me but it looks like the definition of each T[n,t] > depends on the evaluation of the matrix itself on a previous time and so > on iteratively. Since the code does not include any starting condition > at t==0 all three definition enter a infinite loop preventing any useful > evaluation. > > Best regards > > Jacopo > > On 10/26/2011 11:38 PM, Michelle Maul wrote: >> 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 >> >> > > > --

**References**:**Re: Table to calculate faster***From:*Jacopo Bertolotti <jacopo.bertolotti@gmail.com>