Create 1D fitting function for discrete rotational diffusion in a circle

[jmborr]

A 1D fitting function to help quasi-elastic analysis of discrete rotational diffusion on N sites located in a circle. Typical of elongated molecules, like alkanes, but also applicable to methyl rotations.

A more detailed description in http://www.mantidproject.org/DiffRotDiscreteCircle

NOTES FOR THE TESTER:

Download attached files to /tmp. In Mantidplot.Script_Window, load test.py and execute. A fit of the data should yield the followings parameters:

Intensity = 0.745, Radius = 0.876(Angstroms), Decay = 763.6(pico-seconds)

You can plot workspace data_Workspace to visually inspect the fit

You can also use the MantidPlot's fit wizard to perform the fit. Here's the starting fit-string guess that you load to the wizard via Setup->Manage_Setup->Load_From_String:

(composite=Convolution,FixResolution=true,NumDeriv=true;name=TabulatedFunction,FileName="",Workspace=resolution,Scaling=1;(name=DiffRotDiscreteCircle,N=3,NumDeriv=true,Q=1.9,Intensity=1,Radius=1,Decay=10));name=LinearBackground,A0=0.001,A1=0.0001

[jmborr]

This issue was originally trac ticket 8508

[jmborr]

http://trac.mantidproject.org/mantid/raw-attachment/ticket/8508/data.nxs
(uploaded by @jmborr on 2013-12-06T20:23:27)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/8508/test.py
(uploaded by @jmborr on 2013-12-06T20:23:41)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/8508/resolution.nxs
(uploaded by @jmborr on 2013-12-06T20:23:55)

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