For AVERage=R-6, the distance between selected sets of atoms is averaged according to

where runs through all possible combinations of distance restraints between atoms ``" in set 1 and atoms ``" in set 2.

For AVERage=R-3, the distance between selected sets of atoms is averaged according to

where runs through all possible combinations of distance restraints between atoms ``" in set 1 and atoms ``" in set 2.

For AVERage=SUM, the distance between selected sets of atoms is computed by adding up single contributions

where is specified by the MONOmer statement. The scaling by is required, in combination with the SUM averaging option, to scale the distances corresponding to ambiguous peaks in symmetric multimers. The difference between the R-6 option and the SUM option is subtle, and is best illustrated with an example: if two distances are involved in the average, say 3 and 10 Å, the R-6 average will produce an effective distance of 3.37 Å, and the R-6 sum a distance of 2.99 Å, which is probably the desired result for ambiguous NOESY crosspeaks. For this reason, the SUM option should be used rather than the R-6 option to treat ambiguities for observed NOEs.

For AVERage=CENTer, the distance between selected sets of atoms is set to the difference between the geometric centers of the atoms,