UB Matrix Methods

Class methods:

use GQE; 

$ub = UB->create();
$ub = UB->locate();

Methods:

$ret = $ub->get( "itemName"); 	         
$ret = $ub->set( itemName => "itemValue"[,...]); 	

# Examples: 
my ($ub11, $ub12, $ub13, 
    $ub21, $ub22, $ub23, 
    $ub31, $ub32, $ub33) = $ub->get( "ub"); 	         

my $cv_ratio = $ub->get( "cv_ratio"); 
    
$ret = $ub->set( r0 => "(1, 0, 0)");                        # using current angles
$ret = $ub->set( r0 => "($h, $k, $l, $tt, $om, $ch, $ph)"); # with angles

The available UB matrix items are listed below.

cv_ratio
A parameter which is used for the convergence test during the centering of the reflections. The test is passed, if abs( max - new_max)/width $<$ CV_RATIO. The default is 0.01.

h1, h2
The orienation of the reciprocal lattice is determined by the vectors h1 and h2:
$ub->set( h1 => "(1, 0, 0)");

gk
The lattice constants.

gw
The lattice angles.

rk
The reciprocal lattice constants.

rw
The reciprocal lattice angles.

n_iter
The maximum number of iterations that are used to find the center of a reflection. One iteration includes the optimization of OMEGA, TWO_THETA and CHI. The centering procedure terminates earlier, if there are no significant shifts between two consecutive iterations.

np_scan
The number of scan points that are used to center a reflection.

parameter
psi
The angle that used for the FIXED_PSI, FIXED_PHI or FIXED_OM2 scan mode (om2 = omega - two_theta$*$0.5).

reflex_count
The number of reflections.

r0, r1, .+, r19+
r0 to r19 are the reflections that used for the calculation of the UB matrix. If no angles are specified, the current angles are stored:
$ub->set( r0 => "(1, 0, 0)"); # using current angles
$ub->set( r0 => "(1, 0, 0, $tt,$om, $ch,$ph)");

range_chi
range_omega
range_phi
range_two_theta
The scan range for the centering of the reflections.

scan_mode
Specifies a constraint for the transformation of angles to momentum space.
0 Bisecting
1 Fixed psi
2 Constant plane
3 Fixed phi
4 Fixed om2 = (omega-two_theta*0.5)

ub
The elements of the UB matrix:
$ub->set( ub => [$ub11, $ub12, $ub13, $ub21, ..., $ub33]);

ub_from_two
The UB matrix is calculated from the first 2 reflections and the lattice parameters:
$ub->set( ub_from_two => "yes");

ub_from_rafin
The UB matrix is calculated by Rafin, coded by A. Filhol, Institut Laue-Langevin, Grenoble:
$ub->set( ub_from_rafin => "yes");

ub_from_dif4
The UB matrix is calculated by DIF4, coded by K. Eichhorn, Universität Karlsruhe):
$ub->set( ub_from_dif4 => "yes");