Re: Another AppendTo replacement problem
- To: mathgroup at smc.vnet.net
- Subject: [mg118221] Re: Another AppendTo replacement problem
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Sun, 17 Apr 2011 07:51:52 -0400 (EDT)
- References: <iobv13$bfp$1@smc.vnet.net>
The usual trick is to replace AppendTo[list,elem] with list {list,elem}.
The list is going to look like
{{{{{{elem1},elem2},elem3},elem4},elem5},elem6}
At the end you do a list = Flatten[list] and all is fine;
In this case your elements have a structure which has to be protected
against Flatten.
That can be done by replacing the list that contains them with a dummy
head (fl) like this:
Results= {Results, fl[M[[Nbase]], Total[Eigenvalues[matrA[[k]]]]]}
Right after the loop you Flatten and get rid of the head fl:
Results2 = Flatten[Results] /. fl -> List;
For NumBasis =10000 this version is twice as fast, but for NumBasis
=100,000 the speedup is already a factor of 20!
Cheers -- Sjoerd
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On Apr 16, 1:37 pm, Iv=E1n Lazaro <gamins... at gmail.com> wrote:
> I made a mistake in the code. Now it's fine. Sorry.
>
> NumBasis = 10000;
> q = matrA = ma = Table[0, {i, 2}];
> M = RandomComplex[{-1 - I, 1 + I}, {NumBasis, 2, 2}];
> M = Map[Orthogonalize, M];
> matr = RandomComplex[{-1 - I, 1 + I}, {2, 2}]
> Results = {};
>
> Do[{ma[[k]] =
> KroneckerProduct[M[[Nbase, k]], Conjugate[M[[Nbase, k]]]];
> matrA[[k]] = Chop[matr.ma[[k]]];
> matrA[[k]] = matrA[[k]]/Tr[matrA[[k]].matrA[[k]]] // Chop;
> If[k == 2,
> AppendTo[
> Results, {M[[Nbase]], Total[Eigenvalues[matrA[[k]]]]}]];
> }, {Nbase, 1, NumBasis}, {k, 1, 2}];
>
> M = Sort[Results, #1[[2]] < #2[[2]] &][[1, 1]];
>
> Thanks in advance!