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MathGroup Archive 2000

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Pb with ZeroTest

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23608] Pb with ZeroTest
  • From: Jack Michel CORNIL <jmcornil at club-internet.fr>
  • Date: Wed, 24 May 2000 02:16:08 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hello,

I am trying to use the option ZeroTest in the function Inverse
but I desperatly get a crash of the Kernel.
Can someone tell me what is wrong in the following lines ?

In[3]:=
  m = Table[Sin[i + j - 1], {i, 3}, {j, 3}]
  Simplify[Det[m]]
Out[3]=
  {{Sin[1], Sin[2], Sin[3]}, {Sin[2], Sin[3], Sin[4]}, {Sin[3], Sin[4],
Sin[5]}}
Out[4]=
  0
In[5]:=
  mn = 0.001  Round[1000*(m // N)]
  Inverse[mn]
Out[5]=
  {{0.841, 0.909, 0.141}, {0.909, 0.141, -0.757}, 
   {0.141, -0.757, -0.959}}
Out[6]=
  {{7012.83, -7574.5, 7010.12}, {-7574.5, 8182.5, -7572.64}, 
   {7010.12, -7572.64,	7007.21}}

so far so good since the initial matrix is singular !

But if I try to use the option ZeroTest, I crash the kernel :

In[7]:=
  Inverse[mn, ZeroTest -> Function[x, Abs[x] <= 0.001]]

   <<<<< C R A S H >>>>>>


What am I doing wrong ?

Thanks in advance


Jack-Michel CORNIL


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