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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: methods


Set the optimization method


set_method( meth )


The set_method command sets the optimization method to be used in fitting.

  • meth - the optimization method

Available methods are returned by the list_methods command ("ahelp list_methods"). There is a help file for each method, e.g. ("ahelp levmar").

Method Description
levmar The Levenberg-Marquardt method is an interface to the MINPACK subroutine lmdif to find the local minimum of nonlinear least squares functions of several variables by a modification of the Levenberg-Marquardt algorithm (J.J. More, "The Levenberg Marquardt algorithm: implementation and theory," in Lecture Notes in Mathematics 630: Numerical Analysis, G.A. Watson (Ed.), Springer-Verlag: Berlin, 1978, pp.105-116).
moncar The implementation of the moncar method is based on the paper by Storn, R. and Price, K. "Differential Evolution: A Simple and Efficient Adaptive Scheme for Global Optimization over Continuous Spaces." J. Global Optimization 11, 341-359, 1997.
neldermead The implementation of the Nelder Mead Simplex direct search is based on the paper: Jeffrey C. Lagarias, James A. Reeds, Margaret H. Wright, Paul E. Wright "Convergence Properties of the Nelder-Mead Simplex Algorithm in Low Dimensions", SIAM Journal on Optimization,Vol. 9, No. 1 (1998), pages 112-147.
simplex same as the neldermead method

Example 1

sherpa> set_method("neldermead")

Set the optimization method as the Nelder Mead simplex.

Example 2

sherpa> set_method("moncar")

The optimization method is set to "moncar".


See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

set_conf_opt, set_covar_opt, set_proj_opt
set_areascal, set_arf, set_backscal, set_bkg, set_coord, set_counts, set_data, set_exposure, set_grouping, set_quality, set_rmf, set_staterror, set_syserror
levmar, list_iter_methods, list_methods, moncar, neldermead, set_iter_method, set_iter_method_opt, set_method_opt
get_par, set_bkg_model, set_full_model, set_par, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset
set_analysis, set_default_id

Last modified: December 2010
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