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MathGroup Archive 1993

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Re: matrices

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: Re: matrices
  • From: Steven M. Christensen <stevec at yoda.physics.unc.edu>
  • Date: Tue, 30 Mar 93 16:45:17 EST

[With regard to multiplying matrics and scalars posted by
Cetin]
            
MathTensor does your problem very easily  - if you don't
mind indices.

Steve C.

Loading MathTensor for UNIX . . .


========================================================
MathTensor (TM) 2.1.5 (UNIX (R)) (January 1, 1993)
by Leonard Parker and Steven M. Christensen
Copyright (c) 1991-1993 MathSolutions, Inc.
Runs with Mathematica (R) Versions 1.2, 2.0, and 2.1.
Licensed to machine sunny.
========================================================
No unit system is chosen. If you want one,
you must edit the file called Conventions.m,
or enter a command to interactively set units.
Units: {}
Sign conventions: Rmsign = 1 Rcsign = 1
MetricgSign = 1 DetgSign = -1
TensorForm turned on,
ShowTime turned off,
MetricgFlag = True.
=========================================

In[2]:= DefineTensor[A,"A",{{1,2},1}]

In[3]:= DefineTensor[B,"B",{{1,2},1}]

In[4]:= A[ua,lb] A[ub,lc] + A[ua,lb] (B[ub,lc] eps) + (B[ua,lb] eps) A[ub,lc] + (B[ua,lb] eps) (B[ub,lc] eps)

         a   b         b   a         a   b       2  a   b
Out[4]= A   A   + eps A   B   + eps A   B   + eps  B   B
          b   c         c   b         b   c          b   c

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

         a   b       2  a   b          b   a     a   b
Out[5]= A   A   + eps  B   B   + eps (A   B   + A   B  )
          b   c          b   c          c   b     b   c

In[6]:= Quit





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