[phenixbb] question about FFT map coefficients

Pavel Afonine pafonine at lbl.gov
Thu Mar 28 15:43:57 PDT 2013


Hi Mike,

I guess all "FFT map coefficients" tool does is actually encoded in its 
name: Fourier transform map coefficients into actual map (3D function 
computed on a grid). So if you have what you want in input MTZ file then 
you should have what you want in output map file (in Xplor or CCP4 format).

Pavel


On 3/28/13 3:28 PM, Michael Thompson wrote:
> Hello All,
>
> A quick question about the "FFT map coefficients" utility in the GUI:
>
> I have an mtz file with map coefficients that are essentially Fo-Fo for two data sets. I would like to generate a map using these coefficients, but because the subtraction of Fs has already been done, there are some values of FP that are negative. Is "FFT map coefficients" able to handle negative values for FP? If not, I can always change the sign of negative Fs and add 180 to the corresponding model phases, but I was hoping I could avoid this.
>
> Thanks in advance for the help!
>
> Mike
>
>
> P.S. I do know there is an Fo-Fo map option in phenix, but the origin of my map coefficients is more complicated than simply Fo-Fo, so I cannot use this option.
>
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