Ian,
Ah! the old the row is the column depiction of matrices in CCP4 - ha
had forgotten about that! Now at least the output makes sense and the
caveat is to never use brackets.
Thanks to all replies!!
Jens
On Tue, 2012-01-31 at 10:17 +0000, Ian Tickle wrote:
> On 31 January 2012 02:30, Jens Kaiser <[log in to unmask]> wrote:
> > Hi all,
> > we encountered an odd behaviour of REINDEX.
> >
> > Snip form logfile:
> >
> > Data line--- reindex HKL (h+l)/2, -k, (h-l)/2
> > Data line--- end
> >
> > Reflections will be reindexed, and unit cell recalculated
> >
> > Reindexing transformation:
> > (h' k' l') = ( h k l ) ( 1.00000 0.00000 1.00000 )
> > ( 0.00000 -1.00000 0.00000 )
> > ( 0.50000 0.00000 -0.50000 )
> >
> > Obviously, the first line of the matrix is not what we intended to
> > create.
> >
> > inputting the transformation as HKL h/2+l/2, -k, h/2-l/2
> > produces the desired result:
> >
> > Data line--- reindex HKL h/2+l/2, -k, h/2-l/2
> > Data line--- end
> >
> > Reflections will be reindexed, and unit cell recalculated
> >
> > Reindexing transformation:
> > (h' k' l') = ( h k l ) ( 0.50000 0.00000 0.50000 )
> > ( 0.00000 -1.00000 0.00000 )
> > ( 0.50000 0.00000 -0.50000 )
> >
> >
> >
> > Admittedly, the documentation does not use any brackets in the examples,
> > but i would expect REINDEX either to throw an error or treat (h+l)/2
> > like (h-l)/2 but not treat them in the way encountered.
>
> Jens
>
> Reindex is not treating (h+l)/2 any differently from (h-l)/2, they are
> being treated identically, i.e. it is simply ignoring the brackets in
> both cases (which is why expanding the expressions without brackets
> works)..
>
> So (h+l)/2 is being treated as though you had specified h+l/2 and
> (h-l)/2 becomes h-l/2.
>
> Don't forget that the rule for matrix multiplication is row-by-column,
> not row-by-row!
>
> Cheers
>
> -- Ian
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