New features: - New models: cpflux - a variant of cflux for photon flux. heilin - Voigt absorption profiles for the HeI series lyman - Voigt absorption profiles for the HI or HeII series zbabs - EUV ISM attenuation - A new statistic, pgstat, has been added for the case of Poisson-distributed data with a Gaussian-distributed background. The whittle statistic can now be used when fitting averaged power density functions by appending an integer (so eg whittle5 is the statistic to use when fitting a pdf constructed by averaging those from 5 observations). - The old CERN Minuit library, which is used for the migrad, minim, monte, and simplex fitting methods and the improve command, has been replaced by the new version. The minim and monte methods are no longer supported and the new version does not include an improve command. The output from the migrad and simplex fitting methods now looks the same as that from the leven method. Note however that the rules for when to write intermediate fit results are not directly comparable so do not provide a measure of the relative speed of the methods. - Fakeit now has a 'nowrite' option to generate fake spectra without producing output files. This is also now available in the multifake.tcl script command. - Parallel processing capability has been added to the steppar command and can be invoked using the parallel command. - Markov Chain Monte Carlo (the chain command) now uses the Goodman-Weare algorithm by default. Previously the default was Metropolis-Hastings. - After a chain run, the best-fit parameters and statistic are now displayed with "chain info", and are available through the "tclout chain" option. - The default atom_db version used in apec models may now be modified with the ATOMDB_VERSION keyword in the user's Xspec.init file. - Steppar now has a 'delta' option for performing grids centered on the best-fit parameters. - The 'setplot delete' option has been enhanced to allow removal of all or a range of commands. - For external programs calling XSPEC, new wrapper functions have been added for retrieving XFLT keywords from data files. - Norm parameters are now set with a default 'soft' upper limit below their 'hard' upper limit. - In PyXspec, the Fit.statMethod and statTest attributes can now be set for individual spectra. Enhancements previously released as patches to 12.8.0: - AtomDB has been upgraded to version 2.0.2. - The tclout 'stat' and 'statmethod' options can now retrieve the test statistic as well as the fit statistic. - The simftest Tcl script command now takes an optional filename argument for output. - Attributes added to PyXspec classes: Xset.parallel, Fit.statTest. All bug fixes to v12.8.0 released as patches are included in v12.8.1. In addition the following problems have been corrected: - The command history file xspec.hty (in the user's ~/.xspec directory) is now updated when exiting XSPEC with the 'quit' command. Previously it was only updated when exiting with 'exit'. - The 'chain' command can now read/write files in ASCII format when running in the default Goodman-Weare mode. Previously this feature was only available for Metropolis-Hastings chains. - Fix to an array access error in the nthcomp model. - PyXspec fix removes error messages generated when accessing response parameters in Python versions 2.6.x.
Thursday, August 08, 2013
The latest release of XSPEC is now available from the usual place. The release notes are as follows :