Module functions to retrieve the energy grids of source and background datasets.
{Struct_Type | Array_Type} get_energy_axes([Integer_Type])
{Struct_Type | Array_Type} get_energy_baxes([Integer_Type])
{Struct_Type | Array_Type} get_full_energy_axes([Integer_Type])
{Struct_Type | Array_Type} get_full_energy_baxes([Integer_Type])
Error Return Value: NULL
Arguments:
(1) data set number (default 1)
In Sherpa parlance, a ``dataspace'' is an
N-dimensional
grid defined by the independent variables of the dataset
(i.e., x_i in the expression
y = f(x_0, x_1,...,x_(N-1))).
Simple examples include the CHANNELS array in PHA
datasets and the pixel numbers along each axis of FITS images.
The get_energy_axes() function retrieves the dataspace, or
filtered data set axes of the appropriate data set (if no argument
is given, the axes for data set 1 are retrieved). Regardless of
the current Sherpa ANALYSIS setting, this function
returns the dataspace in units of energy (keV). Otherwise, the
function is similar to get_axes().
The function get_full_energy_axes() is similar to
get_energy_axes(), except that get_full_energy_axes()
returns the original, unfiltered dataspace in units of energy. (And
get_energy_baxes() and get_full_energy_baxes()
return filtered and unfiltered dataspaces for the background
associated with the source data set, in units of energy.)
One may display data et al. on the same grid output by
get_energy_axes using the
Sherpa plotting commands
LPLOT DATA et al.
Read the PHA file with the ARF/RMF defined in the header (qso.pha).
Obtain the energy axes information into "foo" and print content of
"foo". Print the value of the third energy in "foo". The mid is NULL, so the
final print command gives an error information.
sherpa> data qso.pha
sherpa> foo=get_energy_axes()
sherpa> print(foo)
axistype = Energy
axisunits = keV
lo = Float_Type[1024]
hi = Float_Type[1024]
mid = NULL
sherpa> print(foo.lo[2])
0.0292
sherpa> print(foo.mid[2])
Type Mismatch: Context requires an array. Scalar not converted
Type Mismatch: print(foo.mid[2]);
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