That is exactly what HYDENS is doing. A good interpolation with small
grid steps should be equally good but with current computers and just a
few hundred or even thousand points to evaluate, a classical Fourier
summation is pretty fast and, for me, easier to program than a proper
cubic-spline interpolation.
Bart
On 11-04-12 08:54 PM, Edward A. Berry wrote:
> Pavel Afonine wrote:
>> Hi Ed,
>>
>> yes, this is the eight-point interpolation, but since you can select to
>> choose very small grid step for the map calculation (grid_step
>> parameter), I hope this should be ok. If necessary, I can add an option
>> so it will give you the map value at the closest grid point instead of
>> interpolation or even both (although I guess the latter would be too
>> much).
>
> What about doing the Fourier summation at the precise location requested,
> in order to not calculate the map or interpolate at all?
> Input would be the mtz file rather than map file.
> eab
>
>> In the next build (dev-728 and up) it will be possible to use a PDB file
>> as a source of points.
>>
>> Pavel.
>>
>> On Tue, Apr 12, 2011 at 9:37 AM, Ed Pozharski <[log in to unmask]
>> <mailto:[log in to unmask]>> wrote:
>>
>> On Fri, 2011-04-08 at 18:06 -0700, Pavel Afonine wrote:
>> > phenix.map_value_at_point map_coeffs.mtz label="2FOFC" point="1 2 3"
>> > point="4 5 6"
>>
>> Cool. Afaiu, this is interpolation. A useful extension would be
>> automatic picking of (x,y,z) from a pdb-file (a la mapman),
>> although a
>> determined person can definitely come up with a script that
>> converts a
>> pdb file into a list of "point" statements.
>>
>> --
>> "Hurry up before we all come back to our senses!"
>> Julian, King of Lemurs
>>
>>
>
--
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Bart Hazes (Associate Professor)
Dept. of Medical Microbiology& Immunology
University of Alberta
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Canada, T6G 2H7
phone: 1-780-492-0042
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