The R-factor is calculated as: R=Σ[ Item2 - Item1*scale]

Σ[ Item1 ]

for two items for each reflection. The desired item identification numbers (IDs) can be specified by the user. The results of the R-factor calculations are analyzed according to sinθ/λ categories as well as categories of various observed intensity ranges. By default, intensity categories are determined as for i=1 ... n, such that 2ⁿ>=1000,000. Also by default, 6 sinθ/λ categories are used to analyze the R-factor values with upper resolution limits of 2, 4, 5, 10 and infinity. The user can specify resolution limits corresponding to the desired sinθ/λ categories to be used.

The program performs the R-factor calculations on the reflection record items in a two-pass process. First, the calculations are done using the user-supplied scale factor (default=1.0). Second, a revised scale factor (obtained from data on the first pass as scale*Σ(item2)/Σ(item1) ) is applied to item1 of the R-factor calculations of the second pass. If group scale factors are much different from final values in the initial pass, the scale factors for the individual bins of sinθ/λ and intensity will still be incorrect for the second pass. This is due to the mixture of scale factors used for items that go into the bins.

Reads the reflection record from the input archive bdf

RCALC 1 0 1302 4302

resol 10.0 5.0 3.0 2.0 1.5

rcode 2 1308

In this example, R-factor statistics are calculated between for data sets 1 and 4. A scale of 1.0 is used and no printing is requested. Sinθ/λ categories will be determined based on the resolution categories of 10.0Å-5.0Å, 5.0Å-3.0Å, 3.0Å-2.0Å, 2.0Å-1.5Å. As determined by the rcode line, only reflections with an rcode value of 2 will be used in the R-factor calculations; the rcode value will be taken from item 1308 in the reflection record.