Extent and increase the sampling density of the time domain in the StretchedExFT fitting function

[jmborr]

The StretchedExFT fitting function calculates the FFT of the stretched exponential using as many time points as bins in the histogram data. This turns out to be insufficient. Many more time points are neccessary to produce a Fourier Transform that can be fitted to the data.

Note to TESTER:

Donwload all attachments and open the python script in the script window of MantidPlot. The header of the script contains the instructions to test the ticket. (the png files are there if you want to take a look at the "experimental" structure factors to be fitted) You can modify the initial guesses for the fitting parameters to see how robust is the fit with respect to the initial guess.

[jmborr]

This issue was originally trac ticket 8624

[jmborr]

http://trac.mantidproject.org/mantid/raw-attachment/ticket/8624/lorentzian1.dat
(uploaded by @jmborr on 2013-12-16T19:56:53)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/8624/lorentzian1.png

(uploaded by @jmborr on 2013-12-16T19:57:15)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/8624/gaussian1.dat
(uploaded by @jmborr on 2013-12-16T20:25:55)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/8624/gaussian1.png

(uploaded by @jmborr on 2013-12-16T20:26:19)

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http://trac.mantidproject.org/mantid/raw-attachment/ticket/8624/test_ticket_8624.py
(uploaded by @jmborr on 2013-12-16T20:27:54)

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