Allow user to rotate source to a different position after ReflectometryReduction has run

[MattKing06]

To Test:

Theta same after rotation
The second and third source position should be the same

from mantid.simpleapi import *
from numpy import sin, pi

dref = mtd['INTER00013463']

print dref.getInstrument().getSource().getPos()

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(dref,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.5037",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)

print IvsLam.getInstrument().getSource().getPos()

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(IvsLam,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.5037",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print IvsQ.getInstrument().getSource().getPos()

Theta smaller after rotation
The last source position should be less than the second (in Y,Z)

from mantid.simpleapi import *
from numpy import sin, pi

dref = mtd['INTER00013463']

print dref.getInstrument().getSource().getPos()

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(dref,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.5037",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)

print IvsLam.getInstrument().getSource().getPos()

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(IvsLam,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.2",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print IvsQ.getInstrument().getSource().getPos()

Theta larger after rotation
Second position of source should be smaller than the last position (in X,Y)

from mantid.simpleapi import *
from numpy import sin, pi

dref = mtd['INTER00013463']

print dref.getInstrument().getSource().getPos()

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(dref,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.5037",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)

print IvsLam.getInstrument().getSource().getPos()

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(IvsLam,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="8.2",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print IvsQ.getInstrument().getSource().getPos()

Release Notes: http://www.mantidproject.org/Release_Notes_3_6_Reflectometry#ReflectometryReductionOne

Fixes #14932

[raquelalvarezbanos]

Merging all the cases in a single script:

from mantid.simpleapi import *
from numpy import sin, pi

Load(Filename=r'D:\SampleData-ISIS\INTER00013463.nxs', OutputWorkspace='INTER00013463')
dref = mtd['INTER00013463']

IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(dref,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.5037",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print "Source was rotated\t", IvsLam.getInstrument().getSource().getPos()

# Theta same after rotation    
IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(IvsLam,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.5037",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print "Same theta\t\t", IvsLam.getInstrument().getSource().getPos()

# Theta smaller after rotation
IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(IvsLam,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="0.2",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print "Smaller theta\t", IvsLam.getInstrument().getSource().getPos()

# Theta larger after rotation
IvsQ, IvsLam, thetaOut=ReflectometryReductionOneAuto(IvsLam,AnalysisMode="MultiDetectorAnalysis",ProcessingInstructions="4", ThetaIn="8.2",
    WavelengthMin=2.2,CorrectionAlgorithm='None',StrictSpectrumChecking=False,CorrectDetectorPositions=True)
print "Larger theta\t", IvsLam.getInstrument().getSource().getPos()

I run this script in debug mode and set a breakpoint at:

return rotationTheta;

to check the relative angles, which turned out to be 0.5037, 0, -0.3037 and 8.0, as expected.

[raquelalvarezbanos]

To further test the changes I added the following couple of lines after each execution of ReflectometryReductionOneAuto():

print IvsQ.getXDimension().getMinimum() / ( 4 * pi * sin (thetaOut * pi / 180 ) / IvsLam.getXDimension().getMaximum())
print IvsQ.getXDimension().getMaximum() / (4 * pi * sin (thetaOut * pi / 180 ) / IvsLam.getXDimension().getMinimum())

The result in all the cases is close to 1, as expected.

[raquelalvarezbanos]

@MattKing06 could you add a line to the release notes?