Package: sherpa
Table of ContentsSherpaLicenseHow To Install SherpaUsing CondaUsing pipBuilding from sourceHistoryRelease HistorySherpaSherpa is a modeling and fitting application for Python. It contains a
powerful language for combining simple models into complex expressions
that can be fit to the data using a variety of statistics and
optimization methods.  It is easily extensible to include user models,
statistics, and optimization methods.  It provides a high-level User
Interface for interactive data-analysis work, such as within a
Jupyter notebook, and it can also be used as a library component,
providing fitting and modeling capabilities to an application.What can you do with Sherpa?fit 1D (multiple) data including: spectra, surface brightness profiles, light curves, general ASCII arraysfit 2D images/surfaces in Poisson/Gaussian regimebuild complex model expressionsimport and use your own modelsuse appropriate statistics for modeling Poisson or Gaussian dataimport new statistics, with priors if required by analysisvisualize the parameter space with simulations or using 1D/2D cuts of the parameter spacecalculate confidence levels on the best fit model parameterschoose a robust optimization method for the fit: Levenberg-Marquardt, Nelder-Mead Simplex or Monte Carlo/Differential Evolution.Documentation for Sherpa is available atRead The Docsand also forSherpa in CIAO.AQuick Start Tutorialis included in thenotebooksfolder and can be opened with anipython notebook.LicenseThis program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version. A copy of the GNU General Public License can be found in theLICENSEfile provided with the source code, or from theFree Software Foundation.How To Install SherpaFull installation instructionsare part of theRead The Docsdocumentation, and should be read if the following is not sufficient.It is strongly recommended that some form ofvirtual environmentis
used with Sherpa.Sherpa is tested against Python versions 3.9, 3.10, and 3.11.The last version of Sherpa which supported Python 2.7 isSherpa 4.11.1.Using CondaSherpa is provided for both Linux and macOS operating systems running
Python 3.9, 3.10, and 3.11. It can be installed with thecondapackage manager by saying$ conda install -c https://cxc.cfa.harvard.edu/conda/sherpa -c conda-forge sherpaUsing pipSherpa is also availableon PyPIand so can be installed
with the following command (which requires that the NumPy package is
already installed).% pip install sherpaBuilding from sourceSource installation is available for platforms incompatible with the
binary builds, or for when the default build options are not sufficient
(such as including support for theXSPECmodel library).
The steps are described in thebuilding from sourcedocumentation.HistorySherpa is developed by theChandra X-ray
Observatoryto provide fitting and modelling
capabilities to theCIAOanalysis package. It
has been released ontoGitHubfor users to
extend (whether to other areas of Astronomy or in other domains).Release History4.15.1: 18 May 20234.15.0: 11 October 20224.14.1: 20 May 20224.14.0: 07 October 20214.13.1: 18 May 20214.13.0: 08 January 20214.12.2: 27 October 20204.12.1: 14 July 20204.12.0: 30 January 20204.11.1: 1 August 20194.11.0: 20 February 20194.10.2: 14 December 20184.10.1: 16 October 20184.10.0: 11 May 20184.9.1: 01 August 20174.9.0: 27 January 20174.8.2: 23 September 20164.8.1: 15 April 20164.8.0: 27 January 2016