Bug in PDBSET

[Phil Evans <pre@mrc-lmb.cam.ac.uk>]

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Clemens Vonrhein writes:
 > There seem to be problems in PDBSET using the ROTATE MATRIX or
 > TRANSFORM command. The SYMGEN card works propperly.
 > 
 > example ( a symmetry operator from P3(2)21 )
 > 
 > SYMGEN -Y,X-Y,Z+2/3
 > does work
 > 
 > ROTA MATRIX -
 >   0 -1 0 -
 >   1 -1 0 -
 >   0  0 1
 > 
 > or
 > 
 > TRANSFORM FRAC -
 >   0 -1 0 -
 >   1 -1 0 -
 >   0  0 1 -
 >   0  0 0.6666667
 > 
 > don't!
 > 
 > There is some checking done for
 > 1) determinant beeing 1
 > 2) matrix multiplied by transpose = unit matrix 1 0 0 0 1 0 0 0 1
 > 
 > Point 2) gives an error flag:
 > 
 >     0 -1 0                0  1  0              1 1 0
 > A = 1 -1 0        A(T) = -1 -1  0     A*A(T) = 1 2 0
 >     0  0 1                0  0  1              0 0 1
 >                                                ^^^^^
 >                                               ????????

This isn't really a bug: ROTATE & TRANSFORM assume the rotation
operates on orthogonal coordinates, so the matrix must be orthonormal.
SYMGEN operates on fractional coordinates. Perhaps this should be made
clearer . . .

	Phil