English

Parameterizing and inverting analytic mappings with unit Jacobian

Complex Variables 2022-01-04 v1

Abstract

Let x=(x1,,xn)Cnx=(x_1,\ldots,x_n)\in {\rm \bf C}^n be a vector of complex variables, denote by A=(ajk)A=(a_{jk}) a square matrix of size n2,n\geq 2, and let φO(Ω)\varphi\in\mathcal{O}(\Omega) be an analytic function defined in a nonempty domain ΩC.\Omega\subset {\rm \bf C}. We investigate the family of mappings f=(f1,,fn):CnCn,f[A,φ](x):=x+φ(Ax) f=(f_1,\ldots,f_n):{\rm \bf C}^n\rightarrow {\rm \bf C}^n, \quad f[A,\varphi](x):=x+\varphi(Ax) with the coordinates fj:xxj+φ(k=1najkxk),j=1,,n f_j : x \mapsto x_j + \varphi\left(\sum\limits_{k=1}^n a_{jk}x_k\right), \quad j=1,\ldots,n whose Jacobian is identically equal to a nonzero constant for any xx such that all of fjf_j are well-defined. Let UU be a square matrix such that the Jacobian of the mapping f[U,φ](x)f[U,\varphi](x) is a nonzero constant for any xx and moreover for any analytic function φO(Ω).\varphi\in\mathcal{O}(\Omega). We show that any such matrix UU is uniquely defined, up to a suitable permutation similarity of matrices, by a partition of the dimension nn into a sum of mm positive integers together with a permutation on mm elements. For any d=2,3,d=2,3,\ldots we construct nn-parametric family of square matrices H(s),sCnH(s), s\in {\rm \bf C}^n such that for any matrix UU as above the mapping x+((UH(s))x)dx+\left((U\odot H(s))x\right)^d defined by the Hadamard product UH(s)U\odot H(s) has unit Jacobian. We prove any such mapping to be polynomially invertible and provide an explicit recursive formula for its inverse.

Keywords

Cite

@article{arxiv.2201.00332,
  title  = {Parameterizing and inverting analytic mappings with unit Jacobian},
  author = {Timur Sadykov},
  journal= {arXiv preprint arXiv:2201.00332},
  year   = {2022}
}

Comments

30 pages

R2 v1 2026-06-24T08:37:53.876Z