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MathGroup Archive 2002

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Re: Changing delayed formula

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35464] Re: Changing delayed formula
  • From: "Carl K. Woll" <carlw at u.washington.edu>
  • Date: Sun, 14 Jul 2002 06:19:35 -0400 (EDT)
  • Organization: University of Washington
  • References: <agomv1$8er$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Julio,

How about

Flatten[Outer[And,Sequence@@des]]

Carl Woll
Physics Dept
U of Washington

"Julio Vera" <jvera at adinet.com.uy> wrote in message
news:agomv1$8er$1 at smc.vnet.net...
>
> Hi,
>
> I have a list of lists. it's length (the number of sublists it
> contains) varies.
>
> In[1]:= des={{11,12,13,14},{21,22,23},{31,32},{41,42,43,44,45}}
>
> Out[1]:= {{11,12,13,14},{21,22,23},{31,32},{41,42,43,44,45}}
>
> The length of each of the sublists is arbitrary, too. So I have this
> list of lengths.
>
> In[2]:= elems=Flatten[Table[Dimensions[des[[i]]],{i,Length[des]}]]
>
> Out[2]:= {4,3,2,5}
>
> I want to obtain the list of all combinations of one element of each
> sublist, bounded by &&. This will be a list of 120 elements, each of
> them with 4 components. I define a delayed formula, and apply Array to
> it (the characters printed as bold are subscripts in the Mathematica
> notebook).
>
> In[3]:=
> cond4[a_,b_,g_,d_]:=des[[1,a]]&&des[[2,b]]&&des[[3,g]]&&des[[4,d]]
>
> In[4]:= combi=Flatten[Array[condLength[des],elems]]
>
> Out[4]:=
> {11&&21&&31&&41,11&&21&&31&&42,11&&21&&31&&43,11&&21&&31&&44,...
>
>   ...14&&23&&32&&42,14&&23&&32&&43,14&&23&&32&&44,14&&23&&32&&45}
>
> Since the length of des varies, I would have to define cond each time.
> For instance:
>
> cond3[a_,b_,g_,d_]:=des[[1,a]]&&des[[2,b]]&&des[[3,g]]
>
> I would like to make a definition for cond that would adapt to these
> changes automatically.
>
> I arrived to this solution, which is not rejected by Mathematica, but
> does not work, either.
>
> In[5]:= d[a_,b_]:=des[[a,b<>"_"]]
>
> In[6]:= Unprotect[ReplaceAll]
>
> Out[6]:= {ReplaceAll}
>
> In[7]:=
>
condLength[des][Table[FromCharacterCode[944+i]<>"_",{i,Length[des]}]]/.{a__}
=AEa:=Apply[And,Table[d[i,FromCharacterCode[944+i]<>"_"],{i,Length[des]}]]
>
> In fact, I quit the kernel and rerun all the cells except the one
> written here as In[3]. If not, the definition for cond4 remains as it
> was. I was not able to clear cond4 individually.
>
> Thanks very much for anything you can suggest.
>
> Best regards,
>
> Julio Vera
>
>




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