Re: ack! simple partitioning problem making my head swim....
- To: mathgroup at smc.vnet.net
- Subject: [mg42079] Re: [mg42050] ack! simple partitioning problem making my head swim....
- From: Tomas Garza <tgarza01 at prodigy.net.mx>
- Date: Wed, 18 Jun 2003 02:11:02 -0400 (EDT)
- References: <200306170943.FAA29237@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Perhaps this will help. If the following is True, then you can multiply
list1.list2, otherwise you can't.
In[1]:=
Dimensions[list1] == Reverse[Dimensions[list2]]
Tomas Garza
Mexico City
----- Original Message -----
From: "cdj" <a_cjones at hotmail.com>
To: mathgroup at smc.vnet.net
Subject: [mg42079] [mg42050] ack! simple partitioning problem making my head swim....
> Hi all,
>
> I'm given 2 (ordered) lists - list1 has elements a_1,..a_n, and list2
> has elements b_1,...,b_n.
>
> As efficiently as possible, I want to determine whether or not these
> lists represent matrices that can be multiplied together. In list
> format, I'm imagining that "a list represents a matrix" means simply:
> the 1st row of the matrix are the first list entries, the second row
> comes next, and so on (just as in the Mathematica command
> Flatten[{{1,2},{3,4}}] = {1,2,3,4}.
>
> (a) It's clear enough that finding a solution to this problem is gonna
> involve comparing the factors in the lengths of the two lists, but
> then it all goes wishywashy in my head. lil help?
>
> (b) Assume there does exist a way of partitioning the two input lists
> so that they form "multiplicatively-friendly" matrices. Is this
> guaranteed to be unique? Or is it possible that there be *several*
> ways to partition given lists into m-friendly matrices?
>
> thanks a bunch for any insights,
>
> cdj
>
>
- References:
- ack! simple partitioning problem making my head swim....
- From: a_cjones@hotmail.com (cdj)
- ack! simple partitioning problem making my head swim....