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Last modified: 4 February 2014


Latest Updates

This document highlights important changes and additions to Sherpa functionality in the CIAO 4.6 Sherpa release.

Latest Version

[New]Sherpa v2 for CIAO 4.6 was released in February 2014, fixing issues with XSpec models while set_analysis("wave") or set_analysis("wavelength").

CIAO 4.6 Updates to Sherpa Functionality

Template Models
  • The ability to interpolate between templates loaded with load_template_model(), so that intermediate parameter values may be found during a fit;
  • The ability to use templates with fitting methods other than gridsearch;
  • The ability to combine templates with other Sherpa models and fit on all parameters (from both the template and continuous models).
New Models
  • Two new 2D models have been added: disk2d and shell2d. These were contributed by Christoph Deil of the HESS project.

XSPEC Models
Save Functions

The default format for all the save_* routines have been changed to write ASCII files, except for save_pha, save_image, and save_table.

Bug Fixes
  • Problems with XSpec models while performing analysis in wavelength-space has been corrected.

  • OSX 10.8 and 10.9 users can now restore their save files.

  • Usage message updated to be consistent with ChIPS.

  • A problem reading grating Type-II HRC PHA files has been corrected.

  • The precision of values returned by get_pvalue_results has been increased.

  • The output format of model min/max values now use %g to provide nicely formatted values (e.g. 100 instead of 1e+02)

  • When user-supplied errors are used with any of the χ2 minimization statistics, the value will now simply be reported as Statistics = chi2.

    Note that for data with user-supplied errors, the errors are calculated with chi2 statistic by default. The users but do not need to use set_stat("chi2") when working with user-supplied errors.

  • Bug with user-defined scales fixed.

  • Corrected the output of calc_stat_info when multiple datasets are defined.

  • ignore_bad() now ignores NaN values in non-PHA datasets.
  • The range of the theta parameter of all 2D models has changed from 0:2π to -2π:2π.

  • Trying to guess model parameters before the data have been loaded now result in a better error message.

  • load_psf models are all now frozen by default.

  • The default minium value for const1d and scale1d are set to allow negative values.

  • absorptionvoigt is no longer allowed to go beyond full absorption (i.e. negative values are disallowed)

  • A bug in how filtering is done in the Seaton extinction model has been corrected.

  • Allow unregistered ModelErr exceptions to be thrown from user models.

  • set_coord now reports the available options when given a bad value

  • set_full_model provides better feedback when trying to mix model objects and model strings.

  • reg_proj clarify error message when incorrect limits are supplied.

  • When using set_full_model the various *_source commands, e.g. get_source do not work. The error message they report however is confusing. This has been reworded.

  • sample_flux has been upgraded to remove a restriction that could lead to an exception being raised that prevented the routine from running.

  • get_draws has been upgrade remove an unnecessary matrix inversion check that could prevent the algorithm from running.

  • Fix to stand-alone Sherpa to no longer require WCS library when trying to

    >>> import sherpa.astro.ui as ui 
  • Various upgrades to support newer version of GCC and OSX's clang compilers.

Last modified: 4 February 2014
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