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Main Authors: Henon, M., Petit, J-M.
Format: Preprint
Published: 1998
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Online Access:https://arxiv.org/abs/math/9805088
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author Henon, M.
Petit, J-M.
author_facet Henon, M.
Petit, J-M.
contents Numerical integrations in celestial mechanics often involve the repeated computation of a rotation with a constant angle. A direct evaluation of these rotations yields a linear drift of the distance to the origin. This is due to roundoff in the representation of the sine s and cosine c of the angle theta. In a computer, one generally gets c^2 + s^2 <> 1, resulting in a mapping that is slightly contracting or expanding. In the present paper we present a method to find pairs of representable real numbers s and c such that c^2 + s^2 is as close to 1 as possible. We show that this results in a drastic decrease of the systematic error, making it negligible compared to the random error of other operations. We also verify that this approach gives good results in a realistic celestial mechanics integration.
format Preprint
id arxiv_https___arxiv_org_abs_math_9805088
institution arXiv
publishDate 1998
record_format arxiv
spellingShingle Good rotations
Henon, M.
Petit, J-M.
Numerical Analysis
65G05 (Primary) 70F15 (Secondary)
Numerical integrations in celestial mechanics often involve the repeated computation of a rotation with a constant angle. A direct evaluation of these rotations yields a linear drift of the distance to the origin. This is due to roundoff in the representation of the sine s and cosine c of the angle theta. In a computer, one generally gets c^2 + s^2 <> 1, resulting in a mapping that is slightly contracting or expanding. In the present paper we present a method to find pairs of representable real numbers s and c such that c^2 + s^2 is as close to 1 as possible. We show that this results in a drastic decrease of the systematic error, making it negligible compared to the random error of other operations. We also verify that this approach gives good results in a realistic celestial mechanics integration.
title Good rotations
topic Numerical Analysis
65G05 (Primary) 70F15 (Secondary)
url https://arxiv.org/abs/math/9805088