It is redundant, but it adds an additional step if someone wanted to calculate something like a 3mFO-2DFc map.
Thanks, Pete -----Original Message----- From: Kevin Cowtan [mailto:[EMAIL PROTECTED] Sent: Mon 7/7/2008 10:18 AM To: Meyer, Peter Cc: [email protected] Subject: Re: [ccp4bb] Definition of Fourier coefficients 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: [email protected] > 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 > > >
