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Physical Sciences and Mathematics Commons

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Mathematics

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Western Washington University

1995

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

The Operator (Sgn X) D²/Dx² Is Similar To A Selfadjoint Operator In L² (R), Branko Ćurgus, Branko Najman Apr 1995

The Operator (Sgn X) D²/Dx² Is Similar To A Selfadjoint Operator In L² (R), Branko Ćurgus, Branko Najman

Mathematics Faculty Publications

Krein space operator-theoretic methods are used to prove that the operator (sgn x) d²/dx² is similar to a selfadjoint operator in the Hilbert space (R).


Lazutkin Coordinates And Invariant Curves For Outer Billiards, Edoh Y. Amiran Mar 1995

Lazutkin Coordinates And Invariant Curves For Outer Billiards, Edoh Y. Amiran

Mathematics Faculty Publications

The outer billiard ball map (OBM) is defined from and to the exterior of a domain, Ω, in the plane as taking a point, q, to another point, q 1, when the line segment with endpoints q and q 1 is tangent to the boundary, ∂Ω (with a chosen orientation), and the point of tangency with the boundary divides the segment in half. Let C be an invariant circle for the OBM on Ω, with ∂Ω smooth with positive curvature. After computing the loss of derivatives between ∂Ω and C, it is shown via KAM theory that …


Historical Development Of The Newton-Raphson Method, Tjalling Ypma Jan 1995

Historical Development Of The Newton-Raphson Method, Tjalling Ypma

Mathematics Faculty Publications

This expository paper traces the development of the Newton-Raphson method for solving nonlinear algebraic equations through the extant notes, letters, and publications of Isaac Newton, Joseph Raphson, and Thomas Simpson. It is shown how Newton's formulation differed from the iterative process of Raphson, and that Simpson was the first to give a general formulation, in terms of fluxional calculus, applicable to nonpolynomial equations. Simpson's extension of the method to systems of equations is exhibited.