The eccentric anomaly of an orbit satisfies Kepler's equation

PHYSICS · Multi-part · Fermi University Physics · Mathematical Methods for Physics · Numerical and computational mathematics · Numerical and computational mathematics

Error, Chance and the Machine, Ch Iteration: nonlinear systems and eigenvalues

Problem

The eccentric anomaly EE of an orbit satisfies Kepler's equation E=M+esin⁡EE = M + e\sin E, where MM is the mean anomaly (radians) and ee is the orbital eccentricity. For an orbit with e=0.6e = 0.6 and M=1.2 radM = 1.2\ \mathrm{rad}, the fixed-point iteration En+1=M+esin⁡EnE_{n+1} = M + e\sin E_n is proposed to solve for EE. ((a)) Find a bound, valid for all real EE, on ∣g′(E)∣|g'(E)| where g(E)=M+esin⁡Eg(E) = M + e\sin E. ((b)) State whether the iteration is guaranteed to converge to the root from any starting value, and give the contraction factor implied by your bound.

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