Web Repository for Zolotarev's First Problem (ZFP) (2018-2023):
Introduction and Description. The goal of this project is to systematically investigate and describe the terms
which enable one to compute algebraically the solution of Zolotarev's First Problem (ZFP) for 4≤n≤13.
ZFP reads as follows: For a prescribed real number s>0 determine the
monic polynomial Zn,s of degree n≥2,
of form xn+(-ns)xn-1+lower degree
terms, which deviates least from zero (in the uniform norm ||.||)
on the interval [-1,1].
If 0≤s≤(tan(π/(2n)))2, then Zn,s is called an improper Zolotarev
polynomial. We consider here only proper Zolotarev polynomials.
In the current form this project is a web repository which contains a list of
Results and Benchmark Problems
for symbolic computation, with the aid of
the CAS Mathematica and Maple.
This page is also intended as a web supplement of research articles
by H.-J Rack (Hagen, Germany) and by R. Vajda (Szeged,
Hungary) on Zolotarev polynomials.
[1] V. A. Malyshev, Algebraic solution of Zolotarev's problem, Algebra i Analiz, 14:4 (2002), 238-240; St. Petersburg Math. J., 14:4 (2003), 711-712
[2]
H.-J. Rack, R. Vajda, Explicit algebraic solution of Zolotarev's First Problem for low-degree polynomials J. Numer. Anal. Approx. Theory, 48(2) (2019), 175-201.
[3]
H.-J. Rack, R. Vajda, An explicit univariate and radical parametrization of the sextic proper Zolotarev polynomials in power form, Dolomites Research Notes on Approximation
Padova University Press, 12(1), pp. 43-50, 2019.
[4]
H.-J. Rack, R. Vajda, An explicit univariate and radical parametrization of the septic proper Zolotarev polynomials in power form (2020) (preprint), arXiv:2002.00503
[5]
H.-J. Rack, R. Vajda, An explicit radical parametrization of Zolotarev polynomials of degree 7 in terms of nested square roots, Advanced Studies: Euro-Tbilisi Mathematical Journal, 14(4) (2021), pp. 37-60.
DOI: 10.3251/asetmj/1932200813
[6]
H.-J. Rack, R. Vajda. Explicit algebraic solution of Zolotarev's First
Problem for low-degree polynomials, Part II. Dolomites Research Notes on Approximation
Padova University Press, 16(3), pp. 75-103, 2023.
For details on ZFP and information on improper and proper Zolotarev
polynomials see the References above (in particular [6]), and the
References given therein.
Below information is provided to solve ZFP (for 4≤n≤13 and the proper case only) algebraically;
for n = 2, 3 see [6, Section 1].
Details about the (radical) parametrizations of Zolotarev polynomials of degree 7 can be found here.
The page is under construction. Extensions and updates are in progress.
2 Three tentative algebraic forms of Zolotarev polynomials depending on
additional parameters α and β, 1<α<β (see References [2] and [6])
2.1 The polynomialsRn,α,βused in the 1st algorithm of [2] and [6]
$R_{4,\alpha,\beta}(x)$:
[Mma input R4alphabeta]
Calculation Rule to get Formula (12) from Formula (11) in [6] (Equioscillation points)
[From Formula (12) to Formula (11)]
2.3 The polynomialsPn,α,βused in the 3rd algorithm of [6]
These polynomials are defined, for all n≥4, by a Formula involving two
determinants, see [6, Formula 14]. The determinants in turn contain the
moments σk=σk(α,β) .
3. Three Variants to determine the concrete α=α0
and
β=β0 if n=n0 and s=s0
are prescribed and thus creating Rn0,α0,β0(x)=
Sn0,α0,β0(x)=
Pn0,α0,β0(x)
, i.e., solving ZFP algebraically, see [6].
3.1 Variant 1 (Malyshev polynomials and largest root index) Degree m(n) of the n-th Malyshev Polynomials
n
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
m(n)
1
2
4
6
8
12
16
18
24
30
32
42
48
48
64
$\left\lfloor\frac{n^2}{4}\right\rfloor$
1
2
4
6
9
12
16
20
25
30
36
42
49
56
64
The n-th Malyshev polynomials for n = 2,3,4,5 are to be found in [1].
For convenience, the n = 4 and n = 5 case is reproduced here in red font.
For n = 6 and n = 7 they have been given in [2] and are reproduced here
for convenience.
For n = 8,9,10,11,12 they have been announced in [2]
and are given here, also for n = 13, for the first time.
Malyshev Polynomials
3.2 Variant 2 (System of two determinant equations)
Variant 2 is inferior to the Variant 3, see [6], and is therefore skipped here.
However, the Formula 23 in [6] is given here exemplarily for n= 2,..,6:
Auxiliary algebraic terms α=αn(β,s) and β=βn(α,s) (n=6,7), see p.87 in [6]
[alpha6 and beta6][alpha7 and beta7]
Worked-out Example of Z4,s via T-Polynomials (referenced to in Remark 6 (v) of [6])
[Z4s along Section 7 of Peherstorfer and Schiefermayr (1999)]
Worked-out Example of Z3,s via recurrent Formula by Vlcek and Unbehauen (referenced to in Remark 6 (vi) of [6])
[Z3s by recursion]
Worked-out Example of 2.6 related to Proposition 2.5
[Example 2.6 in detail]
Algebraic solution of ZFP if n = 6 and s = 2 and coefficients and least deviation expressed in terms of root objects, see Example 5.1 in [6]
[Explicit Z62 with root objects]
Algebraic solution of ZFP if n = 8 and s = 3 and coefficients expressed in terms of root objects, see Appendix 3 in [6]
[Explicit Z83 with root objects]
Algebraic solution of ZFP if n = 9 and s = 4 and coefficients expressed in terms of root objects, see Appendix 3 in [6]
[Explicit Z94 with root objects]
Algebraic solution of ZFP if n = 10 and s = 5 and exemplarily one coefficient expressed in terms of root objects, see Appendix 3 in [6]
[Explicit Z105 with root objects]
Algebraic solution of ZFP if n = 11 and s = 6 and exemplarily one coefficient expressed in terms of root objects, see Appendix 3 in [6]
[Explicit Z116 with root objects]
Algebraic solution of ZFP if n = 12 and s = 7 and exemplarily one coefficient expressed in terms of root objects, see Appendix 3 in [6]
[Explicit Z127 with root objects]
Algebraic solution of ZFP if n = 13 and s = 8 and exemplarily one coefficient expressed in terms of root objects, see Appendix 3 in [6]
[Explicit Z138 with root objects]