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MathGroup Archive 1993

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Re: matrices

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: Re: matrices
  • From: Frank Zizza <zizza at pioneer.willamette.edu>
  • Date: Fri, 2 Apr 93 12:39:35 -0800

If your expressions are symbolic then the following modification to  
Dot will do the trick.

janus> math -noinit
Mathematica 2.1 for NeXT
Copyright 1988-92 Wolfram Research, Inc.

In[1]:= Unprotect[Dot];

In[2]:= Dot[A___, h_?NumberQ B_, C___] := h Dot[A, B, C]

In[3]:= eps /: NumberQ[eps] = True;

In[4]:= Distribute[(A + eps B).(A + eps B)]

                                           2
Out[4]= A . A + eps A . B + eps B . A + eps  B . B

In[5]:= Collect[%, eps]

                                         2
Out[5]= A . A + eps (A . B + B . A) + eps  B . B


Regards,
Frank Zizza
Willamette University
zizza at willamette.edu





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