Abstract
The signature formula of Eisenbud–Levine and Khimshiashvili for computing the Poincaré–Hopf index of a real analytic vector field at an algebraically isolated singularity is well known. We present in this paper an algebraic formula which allows to compute the index in the non–algebraically isolated case when the complex zeros associated to the complexified vector field have codimension one. We also analyse some instances in the codimension 2 case and describe a computer implementation that permits the calculation of the index in both the algebraically and non–algebraically isolated cases.
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Castellanos, V., Castorena, A. & Cruz-López, M. Algebraic and Computational Formulas for the Index of Real Analytic Vector Fields. Results. Math. 59, 125–139 (2011). https://doi.org/10.1007/s00025-010-0066-9
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DOI: https://doi.org/10.1007/s00025-010-0066-9