Using The XSPEC Models Library In Other Programs
For those who wish to incorporate the standard XSPEC model functions library into their own programs, XSPEC provides a set of functions that can be called from external C, C++, or Fortran programs, and can access some of the model functions’ internal data. The C++ functions are listed in the file FunctionUtility.h in the XSFunctions library directory. For C and Fortran access, equivalent wrapper functions are listed in xsFortran.h. The wrapper functions have C-style function declarations, and are also made available to Fortran calling routines via the CERN <cfortan.h> interface.
Interface Routines
The currently provided C/Fortran wrapper functions are (see xsFortran.h for the function signatures):
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FNINIT |
Initializes data directory locations needed by the models. See below for a fuller description. |
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FGABND |
Get an element abundance. |
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FGCHAT |
Get current chatter level setting for model functions’ output verbosity. |
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FPCHAT |
Set the chatter level. Default is 10, higher chatter levels produce more output. |
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FGDATD |
Get the model .dat files path. |
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FPDATD |
Set the model .dat files path. |
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FGMODF |
Get the model ion data path. |
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FGMSTR |
Get a model string value (see XSPEC xset command). |
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FPMSTR |
Set a model string value. |
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FPSLFL |
Load values of a “file” solar abundance table (see abund command). |
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FGSOLR |
Get the solar abundance table setting. |
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FPSOLR |
Set the solar abundance table. |
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FGXSCT |
Get the cross section table setting. |
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FPXSCT |
Set the cross section table. |
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csmgh0 |
Get the cosmology H0 setting (see the cosmo command). |
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csmph0 |
Set H0. |
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csmgl0 |
Get Λ0. |
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csmpl0 |
Set Λ0. |
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csmgq0 |
Get q0. |
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csmpq0 |
Put q0. |
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fzsq |
Computes the luminosity distance, (c/H0)*fzsq. The function is valid for small values of q0*z for the case of no cosmological constant and uses the approximation of Pen (1999 ApJS 120, 49) for the case of a cosmological constant and a flat Universe. The function is not valid for non-zero cosmological constant if the Universe is not flat. |
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Initializing the Models Library
The external program should always call the FNINIT routine prior to any other call into the models library. This initializes the locations of the various data files needed by the models, and also sets the abundance and cross-section tables. Unless the user has overridden the model ion data directory location with the XSPEC_MDATA_DIR environment variable, the initial settings are:
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Model ion data location |
$HEADAS/../spectral/modelIonData |
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Abundance and cross-section .dat files location |
$HEADAS/../spectral/manager |
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Solar abundance table |
angr |
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Photoelectric cross-section table |
bcmc |
Building with the Models Library
The XSFunctions library depends on two lower-level XSPEC libraries, XS and XSUtil, and also the cfitsio library. A Makefile for a small Fortran program linking with the models library therefore may look like this on Linux:
myprog : myprog.o
g77 -g myprog.o -o myprog \
-L/path/to/headas/installed/location/lib \
-lXSFunctions -lXSUtil -lXS -lcfitsio_3.01
myprog.o: myprog.f
g77 -g -c myprog.f