.. algorithm::

.. summary::

.. relatedalgorithms::

.. properties::

Description
-----------

.. warning::

   This algorithm is being developed for a specific instrument. It
   might get changed or even removed without a notification, should
   instrument scientists decide to do so.


Utilises :ref:`algm-EnggFocus` which performs a TOF to dSpacing
conversion using calibrated pixel positions, focuses the values in
dSpacing and then converts them back to TOF. :ref:`algm-EnggFocus`
also perform corrections with Vanadium data.

Then this algorithm calls :ref:`algm-EnggFitPeaks` (as a child
algorithm) which through a sequence of peak fits determines a linear
relationship between dSpacing and measured TOF values in terms of
DIFA, DIFC and TZERO values and provides the these parameters to the
Calibrate algorithm.

This algorithm provides an indirect calibration of the sample
position, that is, a calibration returned in terms of DIFA, DIFC and
ZERO rather than an actual new sample position (hence the reason for
'indirect').

The parameters DIFA, DIFC and ZERO are returned and can be retrieved
as output properties as well. If a name is given in
OutputParametersTableName the algorithm also produces a table
workspace with that name, containing the two output parameters.
Presently the DIFA parameter is always set to zero (see
:ref:`algm-EnggFitTOFFromPeaks`).

See the algorithm :ref:`algm-EnggFocus` for details on the Vanadium
corrections.

.. categories::

.. sourcelink::

Usage
-----

.. include:: ../usagedata-note.txt

**Example - Calculate Difa, Difc, and Zero for EnginX:**

.. testcode:: ExampleCalib

    out_tbl_name = 'out_params'
    ws_name = 'test_engg_data'
    Load('ENGINX00213855.nxs', OutputWorkspace=ws_name)

    # Using precalculated Vanadium corrections. To calculate from scrach see EnggVanadiumCorrections
    van_integ_ws = Load('ENGINX_precalculated_vanadium_run000236516_integration.nxs')
    van_curves_ws = Load('ENGINX_precalculated_vanadium_run000236516_bank_curves.nxs')

    difa1, difc1, tzero1, peaks1 = EnggCalibrate(InputWorkspace=ws_name,
                                        VanIntegrationWorkspace=van_integ_ws,
                                        VanCurvesWorkspace=van_curves_ws,
                                        ExpectedPeaks=[1.09, 1.28, 2.1], Bank='1',
                                        OutputParametersTableName=out_tbl_name)

    difa2, difc2, tzero2, peaks2 = EnggCalibrate(InputWorkspace=ws_name,
                                        VanIntegrationWorkspace=van_integ_ws,
                                        VanCurvesWorkspace=van_curves_ws,
                                        ExpectedPeaks=[1.09, 1.28, 2.1], Bank='2')
    tbl = mtd[out_tbl_name]
    print("The output table has {0} row(s)".format(tbl.rowCount()))


.. testcleanup:: ExampleCalib

   DeleteWorkspace(out_tbl_name)
   DeleteWorkspace(ws_name)
   DeleteWorkspace(van_integ_ws)
   DeleteWorkspace(van_curves_ws)


Output:

.. testoutput:: ExampleCalib

   The output table has 1 row(s)