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It has been noticed in Landau [9] that the inverse eigenvalue problem is intimately related to orthogonal polynomials. Our treatment in section 2 can also be interpreted that way.

To begin with it is clear that tex2html_wrap_inline1041 , tex2html_wrap_inline1043 are polynomials of degree k-1 in tex2html_wrap_inline1047 . Thus (3.5) simply states that the polynomials tex2html_wrap_inline1049 , tex2html_wrap_inline1051 , are the orthonormal polynomials with respect to the scalar product

  equation335

in the space of polynomials of degree n-1. Writing tex2html_wrap_inline1055 in terms of the orthogonal polynomials we get

displaymath1057

or

displaymath1059

with a lower triangular matrix L. This is (3.6). Thus solving the inverse eigenvalue problem, i.e. finding L, boils down to computing the orthogonal polynomials with respect to the scalar product (6.1).

The approach of Gladwell and Willms [7] is essentially equivalent to our treatment of the inverse eigenvalue problems, except that we made the role of transmutation more explicit. For instance, equation (10) of [7] is precisely our relation (3.6) in the form tex2html_wrap_inline1065 .



Frank Wuebbeling
Fri Oct 9 14:01:16 MET DST 1998