Subject: eivals errors with "part: fell off the end"
From: Robert Dodier
Date: Tue, 12 Feb 2013 07:53:24 +0000 (UTC)
On 2013-02-10, andre maute <andre.maute at gmx.de> wrote:
> (%o5) matrix([1,1,1,1,1,1,1],[1,2,3,4,5,6,7],[1,3,6,10,15,21,28],
> [1,4,10,20,35,56,84],[1,5,15,35,70,126,210],
> [1,6,21,56,126,252,462],[1,7,28,84,210,462,924])
> (%i6) eivals(%)
> part: fell off the end.
'eigenvalues' calls 'solve' to solve the characteristic polynomial.
In addition to returning a list (possibly empty) of equations, 'solve'
also assigns the global variable 'multiplicities'. The problem seems to
be that 'eigenvalues' expects 'multiplicities' to add up to the size of
the matrix. In this particular case, one equation is returned and
'multiplicities' is just [1]. There are other solutions of the
characteristic but 'solve' doesn't find them. I guess 'eigenvalues'
needs to be more forgiving about 'multiplicities'.
best
Robert Dodier