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Re: [ccp4bb]: xyzlimit
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The ASU should be determined for most purposes by a library call to
symlib.f:SETLIM. (mapmask and many, but not all, other programs do
this). fft should not be used without a compelling reason. fftbig should
be consistent with mapmask, otherwise it needs fixing. sfall is more
There are two main reasons for inconsistancies:
1. The libraries were written when maps had to be ordered in such a way
as to make an out-of-core fft practical. There are other problems - the
ASU contains duplicate grid points on special sections for most
spacegroups, and whole duplicate volumes in some.
2. Some programs don't use the libraries at all.
The solution to (1) is maps which understand their own symmetry and
better ASU definitions.
The solution to (2) is to shoot any programmer who doesn't use them.
These things are in hand for future software, through the provision of
new libraries and superior firepower. On the whole existing software
will, I'm afraid, have to remain hidden under a GUI.