scaling Fobs/Fcalc discussion

[Alexandre Urzhumtsev/Ourjoumtsev <sacha@lcm3b.u-nancy.fr>]

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Dear Colleagues,

10 year ago (1989, see Appendix to Urzhumtsev et al., J.Appl.Cryst., 22,
500-506) I have pointed out that indeed mathematically the scaling Fobs to
Fcalc and vice versa are different because in the first case there is a
second, absolute but false minima equal to 0 : Scale = 0 and all Bs "equal
to infinity". While I doubt a lot this is a real problem at final
refinement stage, it could appear at the beginning or when the scale factor
is very far from 1.
	In general, I believe that for scale close to one and for reasonable Bs
(is it the case for a given discussion ?) both refinement should behave
similarly therefore the observed difference appears rather due to different
minimisation features realised in the programs.

best regards,

Sasha