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.

========================================================
MathTensor (TM) 2.1.5 (UNIX (R)) (January 1, 1993)
by Leonard Parker and Steven M. Christensen
Runs with Mathematica (R) Versions 1.2, 2.0, and 2.1.
========================================================
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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