[ccp4bb]: physical meanings of positive and negative peaks in DANO Fouriermap

["Q. Steven Xu" <qian@med-biophg.bu.edu>]

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I have two questions regarding the DANO fourier map.

1) What's the difference between the maps calculated with
coeff. F(+)-F(-) and with coeff. F(-)-F(+)? the postive and
negtive peaks would be reversed? 

2) how to explain the positive and negative peaks in such a
map? for instance, if I am searching a sulfur atom which produces the
anomalous signal, I guess I need to search both the positive and negative
peaks, is that right?

Thanks in advance.

regards,
Q. Steven Xu