Re: Dot[]->1
- To: mathgroup at yoda.physics.unc.edu
- Subject: Re: Dot[]->1
- From: a_rubin at dsg4.dse.beckman.com (arthur rubin)
- Date: Fri, 7 Aug 92 07:36:35 PDT
trott at physik.th-ilmenau.de (Trott Michael) writes:
Hi mathgroup,
On simplifying some large expressions via some rules I ended with
expressions of the following type:
Dot[]+Dot[x,y] .
In this expression I would like to replace the first part by 1. So I tried:
(Dot[] + Dot[x,y])/.{Dot[]->1}.
But the result was not what I expected (1+x.y), but rather
1 + 1.x.y .
Can somebody tell me how to do my disired replacement and what happens
in the described example?
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Dot has the attribute "Flat", so that Dot[].x = x; I think the best way to
fix it would be to use:
X_Dot :> If[Length[X]===0,1,X]
Not elegant, but it works.