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RecurrenceTable warning

  • To: mathgroup at smc.vnet.net
  • Subject: [mg102430] RecurrenceTable warning
  • From: green tea <cetech07 at gmail.com>
  • Date: Sun, 9 Aug 2009 06:05:11 -0400 (EDT)

Hello, I'm using Mathematica 7.0.1.

This example is in documentation center.

In[1]:= RecurrenceTable[{a[n + 1] == 3 a[n], a[1] == 7}, a, {n, 1, 5}]
Out[1]= {7, 21, 63, 189, 567}


I added a[n]==b[n].

In[2]:= RecurrenceTable[{b[n] == a[n], a[n + 1] == 3 a[n],
  a[1] == 7}, {a, b}, {n, 1, 5}]
Out[2]= {{7, 7}, {21, 21}, {63, 63}, {189, 189}, {567, 567}}


it works well.
but when I simply swapped a with b, a warning occured.

In[3]:= RecurrenceTable[{a[n] == b[n], b[n + 1] == 3 b[n],
  b[1] == 7}, {b, a}, {n, 1, 5}]

During evaluation of In[3]:= Inverse::matsq: Argument {{1/4,1,-1},
{1/4,0,1}} at position 1 is not a non-empty square matrix. >>

Out[3]= {{7, 7}, {21, 21}, {63, 63}, {189, 189}, {567, 567}}


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