Probably because in the classic implementation it is redundant, D being
derived directly from sigmaa.
Some programs refine D and sigmaa (or equivalent terms, such as Lunin's
alpha and beta) separately. This is conceptually equivalent to deriving
D from sigmaa and refining the scale between Fo and Fc simultaneously
with sigmaa.
Kevin
Meyer, Peter wrote:
> Slightly off-topic from the original question, but is there a reason that most programs don't output D for sigma_a coefficients?
>
> Pete
>
>
> -----Original Message-----
> From: CCP4 bulletin board on behalf of Mayer, Mark (NIH/NICHD) [E]
> Sent: Sat 7/5/2008 2:39 PM
> To: [log in to unmask]
> Subject: [ccp4bb] Definition of Fourier coefficients
>
> Hi,
>
> What do m and D indicate in the Fourier coefficients for a 2mFo-DFc map?
>
> I've dug a bit in web and CCP4 doc but not found an explanation, though I'm sure its there.
>
> Thanks,
>
> Mark
>
>
>
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