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SofQW v1¶
Summary¶
Computes S(Q,w) using a either centre point or parallel-piped rebinning. The output from each method is: CentrePoint - centre-point rebin that takes no account of pixel curvature or area overlap
Polygon - parallel-piped rebin, outputting a weighted-sum of overlapping polygons
NormalisedPolygon - parallel-piped rebin, outputting a weighted-sum of overlapping polygons normalised by the fractional area of each overlap
See Also¶
Properties¶
Name |
Direction |
Type |
Default |
Description |
|---|---|---|---|---|
InputWorkspace |
Input |
Mandatory |
Reduced data in units of energy transfer DeltaE. The workspace must contain histogram data and have common bins across all spectra. |
|
OutputWorkspace |
Output |
Mandatory |
The name to use for the q-omega workspace. |
|
QAxisBinning |
Input |
dbl list |
Mandatory |
The bin parameters to use for the q axis (in the format used by the Rebin v1 algorithm). |
EMode |
Input |
string |
Mandatory |
The energy transfer analysis mode (Direct/Indirect). Allowed values: [‘Direct’, ‘Indirect’] |
EFixed |
Input |
number |
0 |
The value of fixed energy: \(E_i\) (EMode=Direct) or \(E_f\) (EMode=Indirect) (meV). Must be set here if not available in the instrument definition. |
ReplaceNaNs |
Input |
boolean |
False |
If true, all NaN values in the output workspace are replaced using the ReplaceSpecialValues algorithm. |
EAxisBinning |
Input |
dbl list |
The bin parameters to use for the E axis (optional, in the format used by the Rebin v1 algorithm). |
|
DetectorTwoThetaRanges |
Input |
A table workspace use by SofQWNormalisedPolygon containing a ‘Detector ID’ column as well as ‘Min two theta’ and ‘Max two theta’ columns listing the detector’s min and max scattering angles in radians. |
||
Method |
Input |
string |
Centre |
Defines the method used to compute the output. Allowed values: [‘Centre’, ‘Polygon’, ‘NormalisedPolygon’] |
Description¶
This algorithm is for use by inelastic instruments and takes as its input a workspace where the data’s been reduced to be in units of energy transfer against spectrum number (which can be seen as equivalent to angle, with the angle being taken from the detector(s) to which the spectrum pertains).
This algorithm can operate in one of three modes. Each mode simply runs a different algorithm to perform the computation:
Centre: performs a basic centre-point rebinning, see SofQWCentre v1
Polygon: performs a parallel-piped rebin, taking into account the curvature of the output bins, see SofQWPolygon v1
NormalisedPolygon: performs the same rebin as Polygon but the output bins normalised by the contributing overlap area, see SofQWNormalisedPolygon v1
The energy binning will not be changed by this algorithm, so the input workspace should already have the desired bins (though this axis can be rebinned afterwards if desired). The EMode and EFixed parameters are used for the calculation of \(Q\).
If the input workspace is a distribution (i.e. counts/meV ) then the output workspace will similarly be divided by the bin width in both directions (i.e. will contain counts/meV/(1/Angstrom) ).
Workflow¶
Usage¶
Example - simple transformation of inelastic workspace:
# create sample inelastic workspace for MARI instrument containing 1 at all spectra values
ws=CreateSimulationWorkspace(Instrument='MAR',BinParams='-10,1,10')
# convert workspace into MD workspace
ws=SofQW(InputWorkspace=ws,QAxisBinning='-3,0.1,3',Emode='Direct',EFixed=12)
print("The converted X values are:")
print(ws.readX(59)[0:10])
print(ws.readX(59)[10:21])
print("The converted Y values are:")
print(ws.readY(59)[0:10])
print(ws.readY(59)[10:21])
Output:
The converted X values are:
[-10. -9. -8. -7. -6. -5. -4. -3. -2. -1.]
[ 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.]
The converted Y values are:
[12. 18. 18. 18. 18. 21. 18. 18. 21. 12.]
[18. 21. 24. 24. 24. 21. 24. 33. 39. 45.]
Categories: AlgorithmIndex | Inelastic\SofQW
Source¶
C++ header: SofQW.h
C++ source: SofQW.cpp