Re: [ccp4bb] How to subtract one electron density map from another

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From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
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Subject: Re: How to subtract one electron density map from another
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-03-23

Qing Xie wrote:
> Hi,
> I'm trying to get the difference map by subtracting the native
> electron density map from the complex electron density map. MAPMASK
> has a function of ADD/MULT, but I don't know how to use it?
> Any other ways to attack this problem in real space?
>
> Thanks in advance,
>
> Qing
>
>
Yes - mapmask will do it providing you ADD SCALE -1 fpr one map then
MAP ADD

But there isa no adjustment for scaling one map to the other.
It is better to do a difference map use F1=Fcomplex and F2 = Fnative and
the phases/FOM from the model.
(see Map Utilities)
Make sure you have scaled F1 and F2 together (scaleit will do it) AFTER
calculating the PHIC/FOM.

Most SF generating programs (REFMAC, SFALL, maybe Clipper utilitiy?)
output a Fobs scaled to Fcalc so you need to rescale the other F again..
Eleanor

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CCP4bb <-- 2007 <-- March 2007 <-- 23 March 2007

Previous message:
Subject: Re: Highest shell standards
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-03-23

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From: Charles Ballard C {- dot -} C {- dot -} Ballard {- at -} DL {- dot -} AC {- dot -} UK
Date: 2007-03-23