### Abstract

The renormalization group (RG) method for differential equations is one of the perturbation methods which allows one to obtain invariant manifolds of a given ordinary differential equation together with approximate solutions to it. This article investigates higher order RG equations which serve to refine an error estimate of approximate solutions obtained by the first order RG equations. It is shown that the higher order RG equation maintains the similar theorems to those provided by the first order RG equation, which are theorems on well-definedness of approximate vector fields, and on inheritance of invariant manifolds from those for the RG equation to those for the original equation, for example. Since the higher order RG equation is defined by using indefinite integrals and is not unique for the reason of the undetermined integral constants, the simplest form of RG equation is available by choosing suitable integral constants. It is shown that this simplified RG equation is sufficient to determine whether the trivial solution to time-dependent linear equations is hyperbolically stable or not, and thereby a synchronous solution of a coupled oscillators is shown to be stable.

Original language | English |
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Pages (from-to) | 1991-2019 |

Number of pages | 29 |

Journal | Journal of Differential Equations |

Volume | 246 |

Issue number | 5 |

DOIs | |

Publication status | Published - Mar 1 2009 |

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### All Science Journal Classification (ASJC) codes

- Analysis
- Applied Mathematics

### Cite this

*Journal of Differential Equations*,

*246*(5), 1991-2019. https://doi.org/10.1016/j.jde.2008.11.012

**Simplified renormalization group method for ordinary differential equations.** / Chiba, Hayato.

Research output: Contribution to journal › Article

*Journal of Differential Equations*, vol. 246, no. 5, pp. 1991-2019. https://doi.org/10.1016/j.jde.2008.11.012

}

TY - JOUR

T1 - Simplified renormalization group method for ordinary differential equations

AU - Chiba, Hayato

PY - 2009/3/1

Y1 - 2009/3/1

N2 - The renormalization group (RG) method for differential equations is one of the perturbation methods which allows one to obtain invariant manifolds of a given ordinary differential equation together with approximate solutions to it. This article investigates higher order RG equations which serve to refine an error estimate of approximate solutions obtained by the first order RG equations. It is shown that the higher order RG equation maintains the similar theorems to those provided by the first order RG equation, which are theorems on well-definedness of approximate vector fields, and on inheritance of invariant manifolds from those for the RG equation to those for the original equation, for example. Since the higher order RG equation is defined by using indefinite integrals and is not unique for the reason of the undetermined integral constants, the simplest form of RG equation is available by choosing suitable integral constants. It is shown that this simplified RG equation is sufficient to determine whether the trivial solution to time-dependent linear equations is hyperbolically stable or not, and thereby a synchronous solution of a coupled oscillators is shown to be stable.

AB - The renormalization group (RG) method for differential equations is one of the perturbation methods which allows one to obtain invariant manifolds of a given ordinary differential equation together with approximate solutions to it. This article investigates higher order RG equations which serve to refine an error estimate of approximate solutions obtained by the first order RG equations. It is shown that the higher order RG equation maintains the similar theorems to those provided by the first order RG equation, which are theorems on well-definedness of approximate vector fields, and on inheritance of invariant manifolds from those for the RG equation to those for the original equation, for example. Since the higher order RG equation is defined by using indefinite integrals and is not unique for the reason of the undetermined integral constants, the simplest form of RG equation is available by choosing suitable integral constants. It is shown that this simplified RG equation is sufficient to determine whether the trivial solution to time-dependent linear equations is hyperbolically stable or not, and thereby a synchronous solution of a coupled oscillators is shown to be stable.

UR - http://www.scopus.com/inward/record.url?scp=58749091975&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=58749091975&partnerID=8YFLogxK

U2 - 10.1016/j.jde.2008.11.012

DO - 10.1016/j.jde.2008.11.012

M3 - Article

AN - SCOPUS:58749091975

VL - 246

SP - 1991

EP - 2019

JO - Journal of Differential Equations

JF - Journal of Differential Equations

SN - 0022-0396

IS - 5

ER -