Help with a Fold/Outer one-liner
- To: mathgroup at smc.vnet.net
- Subject: [mg28220] Help with a Fold/Outer one-liner
- From: "Emilio Martin-Serrano Sobrino" <emilio.martin at sema.es>
- Date: Thu, 5 Apr 2001 03:00:33 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hi math groupers:
Could anyone give me a hand with this?
Let {m[1],m[2], m[3],m[4]} be a list of tensors over N^4 . I want to apply
the following function to the previous list:
With[{vars = {x1,x2,x3,x4}}, Fold[Outer[D, #, vars]&, m1,{m2,m3,m4}]] (*let
us consider {x1,x2,x3,x4} as the actual dimension names } *).
In fact the length of the list and the dimensions should not matter, I put
"4" to make things clearer.
And I did this:
With[{vars =(*Extract de list of the dimensions names to differentiate*)},
Fold[Outer[D, #, vars]&, First[List@@#],Drop[List@@#,1]]]&/@
Sequence[m1,m2,m3,m4];
But it does not work.
My main problem is with how to extract the dimension names (or the length)
Any help?
Regards
Emilio Martin-Serrano
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