Volume 13, Issue 5
The Unstable Mode in the Crank-Nicolson Leap-Frog Method is Stable

N. Hurl, W. Layton, Y. Li & M. Moraiti

Int. J. Numer. Anal. Mod., 13 (2016), pp. 753-762

Published online: 2016-09

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  • Abstract

This report proves that under the time step condition Δt|Λ| ‹ 1 (|⋅| = Euclidean norm) suggested by root condition analysis and necessary for stability, all modes of the Crank- Nicolson Leap-Frog (CNLF) approximate solution to the system \frac{du}{dt}+ Au + Λu = 0; for t > 0 and u(0) = u_0; where A + A^T is symmetric positive definite and Λ is skew symmetric, are asymptotically stable. This result gives a sufficient stability condition for non-commutative A and Λ, and is proven by energy methods. Thus, the growth, often reported in the unstable mode, is not due to systems effects and its explanation must be sought elsewhere.

  • Keywords

IMEX method Crank-Nicolson Leap-Frog CNLF unstable mode computational mode

  • AMS Subject Headings

65

  • Copyright

COPYRIGHT: © Global Science Press

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@Article{IJNAM-13-753, author = {N. Hurl, W. Layton, Y. Li and M. Moraiti}, title = {The Unstable Mode in the Crank-Nicolson Leap-Frog Method is Stable}, journal = {International Journal of Numerical Analysis and Modeling}, year = {2016}, volume = {13}, number = {5}, pages = {753--762}, abstract = {This report proves that under the time step condition Δt|Λ| ‹ 1 (|⋅| = Euclidean norm) suggested by root condition analysis and necessary for stability, all modes of the Crank- Nicolson Leap-Frog (CNLF) approximate solution to the system \frac{du}{dt}+ Au + Λu = 0; for t > 0 and u(0) = u_0; where A + A^T is symmetric positive definite and Λ is skew symmetric, are asymptotically stable. This result gives a sufficient stability condition for non-commutative A and Λ, and is proven by energy methods. Thus, the growth, often reported in the unstable mode, is not due to systems effects and its explanation must be sought elsewhere.}, issn = {2617-8710}, doi = {https://doi.org/}, url = {http://global-sci.org/intro/article_detail/ijnam/463.html} }
TY - JOUR T1 - The Unstable Mode in the Crank-Nicolson Leap-Frog Method is Stable AU - N. Hurl, W. Layton, Y. Li & M. Moraiti JO - International Journal of Numerical Analysis and Modeling VL - 5 SP - 753 EP - 762 PY - 2016 DA - 2016/09 SN - 13 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/ijnam/463.html KW - IMEX method KW - Crank-Nicolson Leap-Frog KW - CNLF KW - unstable mode KW - computational mode AB - This report proves that under the time step condition Δt|Λ| ‹ 1 (|⋅| = Euclidean norm) suggested by root condition analysis and necessary for stability, all modes of the Crank- Nicolson Leap-Frog (CNLF) approximate solution to the system \frac{du}{dt}+ Au + Λu = 0; for t > 0 and u(0) = u_0; where A + A^T is symmetric positive definite and Λ is skew symmetric, are asymptotically stable. This result gives a sufficient stability condition for non-commutative A and Λ, and is proven by energy methods. Thus, the growth, often reported in the unstable mode, is not due to systems effects and its explanation must be sought elsewhere.
N. Hurl, W. Layton, Y. Li & M. Moraiti. (1970). The Unstable Mode in the Crank-Nicolson Leap-Frog Method is Stable. International Journal of Numerical Analysis and Modeling. 13 (5). 753-762. doi:
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