few easy questions
- To: mathgroup@smc.vnet.net
- Subject: [mg11451] few easy questions
- From: "Arturas Acus" <acus@itpa.lt>
- Date: Thu, 12 Mar 1998 01:34:02 -0500
- Return-Receipt-To: "Arturas Acus" <acus@itpa.lt>
Hello, Group
1)
Why this two substitutions act differently In[9]:=
{Dt[a], Sin[a]} //. {Dt[x_] :> 1, Sin[x_] :> 1} Out[9]=
{Dt[a], 1}
Of course the dirty trick bellow works, but I am still interesting
what's
going.
In[10]:=
Dt[a] //. {x_Dt :> mydt[x], mydt[x_] :> 1}
2)
Thanks to P. Abbot I know about number of packages for tensor
manipulation. I was rather interesting in "EinS" and planned to use it
as a starting point of my own purposes. Unfortunately, the package is
encoded, (like STensor, and MathTensor) and the author do not intended
to put the actual
code for free use. So I have few questions about that format a)Is the
format simple encoding or it includes some precompilation, compression,
etc.?
b) How the encoding acts on general performance of the code(speed up?)?
c) Do algorithms on manipulation of dummy indices are such a huge
problem ?
d)How to make this encoding myself ? ( I could not hope that anybody
could answer me how to decode them :-)
).What is WRI opinion on the topic.
Sincerely,
Arturas Acus
Institute of Theoretical
Physics and Astronomy
Gostauto 12, 2600,Vilnius
Lithuania
E-mail: acus@itpa.lt
Fax: 370-2-225361
Tel: 370-2-612906