144 Normat 54:3, 144 (2006)

Summary in English

Jens Erik Fenstad, Bent Birkeland,

1934 – 2006 (Norwegian).

Obituary for Professor Bent Birkeland,

who died on April 9 this year. Birke-

land was a highly regarded mathemati-

cian and teacher, with wide interests. He

was President of the Norwegian Mathe-

matical Society 1995–2000.

Christian Berg, Orthogonal polyno-

mials and the Hilbert matrix. (Danish).

The article gives a short introduction

to the theory of orthogonal polynomials

and their connection to Hankel mat-

rices, i.e. matrices such that the i, j’th

element only depends on the sum of the

indices. Important examples are the Hil-

bert matrices, for which the elements

are reciprocals of natural numbers, and

the analogous “Filbert matrices”, where

the elements are reciprocals of Fibonac-

ci numbers.

As an important example of ortho-

gonal p olynomials the author considers

the Legendre polynomials. They have

integer coeﬃcients, and it is shown how

this can be used to prove that the inver-

se of the Hilbert matrices have integer

entries.

At the end some recent results are

mentioned illuminating the relationship

between the indeterminate moment pro-

blem and diﬀerent areas of mathema-

tics.

A research paper by the author in

English: Fibonacci numbers and ortho-

gonal polynomials is going to appear in

J. Comput. Appl. Math. and can be re-

trieved at www.math.ku.dk/~berg/.

Bjørn Toldbod and Uﬀe Thomas

Jankvist, Report from a Mars Mission

(Danish).

The article investigates some of the

mathematics involved in the Mars mis-

sion of 2004 called the Mars Explora-

tion Rovers mission (MER). MER was

the result of many years of work done

at NASA’s Jet Propulsion Laboratory

which serves as the basis of the investi-

gation. The focus of the article is main-

ly on the use and development of mat-

hematics at the JPL. In particular, the

article discusses the possibility of doing

mathematical work contributing to ba-

sic mathematical research at an institu-

tion like the JPL.

Many factors limit this possibility.

These factors include deadlines, high

demand for reliability leading to a lot

of reuse from mission to mission, as well

as the fact that much of the mathema-

tics used is hidden in software. The ar-

ticle concludes that although the work

done at the JPL concerning the Mars

mission required a solid mathematical

foundation, the work had little impact

on basic mathematical research. Instead

the JPL plays an equally important role

for mathematics – that of a consumer.