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MathGroup Archive 1989

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bug in cross product

  • To: mathgroup
  • Subject: bug in cross product
  • From: mrk at athena.Princeton.EDU
  • Date: Fri, 24 Mar 89 15:53:33 CST

There is a bug in the Mathematica Package CrossProduct.m. Following is a sample
session illustrating the problem:

In[1]:= <<CrossProduct.m

In[2]:= Cross[a,b]^2

              2
Out[2]= -a . b  + a . a b . b

Note that this is incorrect (in the first term the a should be squared).
If you do the following the answer comes out correct:

In[3]:= Cross[a,b] . Cross[a,b]

Out[3]= -a . (b a . b) + a . (a b . b)

Mark Dragovan
Physics Dept, Princeton University
mrk at athena.princeton.edu





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