Well according to Google this paper (JCS, 1936) contains the phrase
"magnitudes of the structure amplitude factors (F)":
http://www.google.co.uk/search?hl=en&q=%22magnitudes+of+the+structure+am
plitude+factors%22&btnG=Search&meta= .
It seems that "structure amplitude factor" is what we have now
abbreviated to "structure factor", i.e. it would appear that "amplitude"
was being used in a different sense from what we are using. Logically
the magnitude of a structure amplitude factor should be a "structure
amplitude factor magnitude", so I guess it was not surprising that it
was abbreviated to just "structure amplitude". I hardly think you could
call it a "structure amplitude factor amplitude"!
-- Ian
> -----Original Message-----
> From: [log in to unmask]
> [mailto:[log in to unmask]] On Behalf Of Bernhard Rupp
> Sent: 12 January 2009 17:44
> To: [log in to unmask]; [log in to unmask]
> Subject: Re: [ccp4bb] structure (factor) amplitude
>
> Hmmm.....
>
> Sacha just threw another wrench into that discourse. Seems we are
> also faced with a duality problem here:
>
> Coming from a mathematical point of view treating F as a
> complex number,
>
> structure factor magnitude or
> structure factor modulus
>
> is more logical and more direct.
>
> If you are taking the physical pov (let's not go into detail
> there, btw)
> *interpreting* the complex number as wave description
> (and here I must say Ian's point wrt song title/name is well taken)
>
> structure factor amplitude
>
> is more logical.
>
> Best, BR
>
> Dear Bernhard,
>
> First of all, happy new year !
>
> > I am getting conflicting comments on the use of
> > 'structure factor amplitude'
> > vs. just
> > 'structure amplitude' for |F|.
>
> Even when "structure factor amplitude" (or "magnitude",
> following some
> english-speaking persons?? If I am right I learned that
> M.Woolfson prefers
> "magnitude". My English is too poor to judge) seems to be
> long, it seems to
> be correct and have a clear meaning. That is not the case for
> "structure
> amplitude". In that sens I agree with Ethan and Pavel.
>
> With best wishes !
>
> Sacha
>
>
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