Numerical algorithm and complexity analysis for diagonalization of multivariate homogeneous polynomials
Lishan Fang, Hua-Lin Huang, Yuechen Li
TL;DR
The paper presents a center-based framework for diagonalizing multivariate homogeneous polynomials via Harrison's center theory. It establishes a polynomial-time criterion (detect nondegeneracy, compute center, and detect diagonalizability) and an iterative diagonalization algorithm that, when feasible, yields a diagonal sum of $d$-th powers; nonlinear steps may be NP-hard, but numerical results show practical efficiency. The work provides explicit complexity costs for each component in terms of $n$, $d$, and the term count $t$, and situates the method relative to randomized factorization, tensor methods, and Milnor-algebra approaches. Its significance lies in delivering a deterministic, algebraic route to diagonalization with documented performance gains and clear avenues for extension to multiple polynomials and to Waring-type decompositions.
Abstract
We study the computational complexity of a diagonalization technique for multivariate homogeneous polynomials, that is, expressing them as sums of powers of independent linear forms. It is based on Harrison's center theory and consists of a criterion and a diagonalization algorithm. Detailed formulations and computational complexity of each component of the technique are given. The complexity analysis focuses on the impacts of the number of variables and the degree of given polynomials. We show that this criterion runs in polynomial time and the diagonalization process performs efficiently in numerical experiments. Other diagonalization techniques are reviewed and compared in terms of complexity.
