Make the peak radius an attribute of the function.

[mantid-roman]

This issue was originally TRAC 5545

The PeakFunction has a default and quite small 'peak radius' - a cut-off distance for the peak wings. It is a good thing for algorithms such as FindPeaks but can be a problem for a user who is unfamiliar with it.

There should not be a global radius. It should be an attribute with different defaults for each peak type.

[mantid-roman]

@NickDraper (2012-08-10T12:43:53):
Moved at the end of release 2.2

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@NickDraper (2012-10-28T11:39:02):
Moved to milestone 2.4

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@NickDraper (2013-01-28T09:23:11):
Moved at the code freeze for release 2.4

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@NickDraper (2013-04-29T09:49:45):
Moved to r2.6 at the end of r2.5

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@NickDraper (2013-07-26T13:54:59):
Moved to backlog at the code freeze for R2.6

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@NickDraper (2014-02-28T16:53:47):
Please assess if ticket is still valid and add a description to the ticket

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@NickDraper (2014-03-03T13:47:12):
What effect would this have on the creating and adjusting a peak using the GUI.

The Very Large comment is slightly concerning.

Rather than a set default could we not try to assess the HWHM using a simple walk out from the centre of the peak?

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@mantid-roman (2014-03-03T15:28:54):

• This won't have any negative effect on the GUI.
• Very large means that practically there is no cut-off and no loss of accuracy.
• The dynamic cut-off is possible but it will be slower than the fixed value or each peak will have to implement the walk.
• Maybe this 'radius' should become an attribute? This would make it more visible and flexible.

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@NickDraper (2014-12-08T10:25:31):
Moved to the backlog at the code freeze of R3.3

[mantid-roman]

http://trac.mantidproject.org/mantid/raw-attachment/ticket/5545/Lorentz-and-Gauss.png

(uploaded by @mantid-roman on 2014-03-03T14:34:02)

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