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In principle there's no reason why you can't invert the hand of the indices, as long as the program which does it also takes care to convert any hand-dependent columns such as anomalous differences, F+/F- etc in the appropriate manner at the same time. The program will also need to convert any phase or phase-coefficient columns, but it will have to do this anyway, even if the hand is not inverted, in those cases where the space group contains screw axes (since then you will get phase shifts on reindexing for certain subsets of reflections). So if the data consist only of I's or F's without anomalous data or phases then inverting the hand will have absolutely no effect (it's called "Friedel's Law"). I note from the documentation that reindex will invert the hand if the keyword 'LEFT' is supplied, though whether it then treats the anomalous data and phases correctly is anyone's guess! The question is really whether it's likely ever to be _necessary_ to invert the hand; this will depend on the reciprocal space asymmetric unit chosen by the processing program. One could imagine a situation where the a.u. chosen by one processing program was on a different hand from the a.u. required by another. In such a situation you would have no choice but to invert the hand of the indices, though I suspect you would be better off doing it with CAD which will do it reliably, rather than reindex which may not (judging by the comments in the reindex code!). Whether such a situation ever occurs in practice, I don't know, maybe not. Cheers -- Ian On 29 May 2012 09:57, Graeme Winter <[log in to unmask]> wrote: > Hello Qixu Cai, > > What you want is a reindexing operator which permutes the axes rather > than one which changes the sign of an axis. The easiest way to do this > is with pointless: > > pointless hklin input.mtz hklref reference.mtz hklout output.mtz > > and let pointless figure out the right operation to use. You may find > the following helpful: > > http://www.ccp4.ac.uk/html/reindexing.html > > Best wishes, > > Graeme > > On 29 May 2012 09:48, Qixu Cai <[log in to unmask]> wrote: >> Dear all, >> >> I have a dataset at P321 space group. And I want to reindex from (h,k,l) to >> (k,h,l) or (h,k,-l), because I want to merge this dataset to the native >> dataset. >> At first, I used the "reindex" program in CCP4i, and got an error: (either >> for (k,h,l) or (h,k,-l)) >> >> ================================================ >> Data line--- reindex HKL h, k, -l >> Data line--- end >> >> $TEXT:Warning: $$ comment $$ >> WARNING: !!!! Reindexing matrix INVERTS hand !!!! >> $$ >> REINDEX: !!!! You are NOT allowed to do this - Changing all signs in >> reindexing matrix >> Times: User: 0.0s System: 0.0s Elapsed: 0:00 >> ================================================= >> >> Could you please tell me the reason? >> >> At last, I converted the mtz file to CNS format, and write a script to >> exchange the h and k, and converted to mtz file. >> When I tried to use "cad" to merge this dataset to the native dataset, if I >> chose "Automatically check and enforce consistent indexing between different >> files", >> the index would be changed back to the original index. Why? >> >> Thank you very much for your attention. >> >> Best wishes, >> >> Qixu Cai