Teixeira, Ricardo Emanuel CunhaBebiano, NatáliaProvidência, João da2012-08-292012-08-292008-06-01Teixeira, Ricardo; Bebiano, Natália; Providência, João da (2008). «Flat portions on the boundary of the indefinite numerical range of 3×3 matrices». "Linear Algebra and its Applications", 428, nº 11-12, 2863-2879.0024-3795http://dx.doi.org/10.1016/j.laa.2008.01.017http://hdl.handle.net/10400.3/1457Copyright © 2008 Elsevier Inc. All rights reserved.We focus on complex 3×3 matrices whose indefinite numerical ranges have a flat portion on the boundary. The results here obtained are parallel to those of Keeler, Rodman and Spitkovsky for the classical numerical range.engIndefinite Numerical RangeIndefinite Inner Product SpacePlane Algebraic CurveFlat Portionjournal article