4.10.5 - Crystal Setting Finder - JdlSetting3DFT

John W. Campbell

4.10.5.1 Introduction

Class, constructor and methods:

4.10.5.2 Class Details

Package:

Jdl.JdlPX;

Class name:

JdlSetting3DFT

Class definition:

public class JdlSetting3DFT

Extends:

Object

Implements:

none

Actions:

none

4.10.5.3 Accessible Fields

static boolean show_debug

4.10.5.4 Constructor

4.10.5.4.1 Introduction

Constructor:

4.10.5.4.2 Constructor

Constructor Definition:

public JdlSetting3DFT(JdlSearchImageSpotsList spotlist, JdlCell cell, int latt, Jdl3x3 umat, JdlPositionedDetector posdet, double x_cen, double y_cen, double pixsiz_x, double pixsiz_y, JdlDistortionCorrections distor)

Parameters List:

spotlist

A list of spot positions found from an image search.

cell

The cell parameters.

latt

The lattice type 1-7.

umat

The 'U' matrix

posdet

The positioned detector details.

x_cen

The 'x' centre position of the image in rasters.

y_cen

The 'y' centre position of the image in rasters.

pixsiz_x

The 'x' pixel size in mm.

pixsiz_y

The 'y' pixel size in mm.

distor

A distortions correction object - may be null if not required.

4.10.5.5 Setting Method

4.10.5.5.1 Introduction

Methods:

4.10.5.5.2 Find setting - findCrystalSetting

Method Definition:

public JdlSettingSolution[] findCrystalSetting(int method, double ang_tol, JdlProgressHandler progress)

Parameters List:

method

Method number 1 or 2. Two possible methods are available for finding peaks in a Fourier transform corresponding to the cell vectors.
Method 1: Rotate a vector in appropriate steps around two angles, one through 90 degress and the other through 360 degrees (As done in MOSFLM program) and look for peaks along those vectors at the cell distances (looking at a grid of 9 points around each such position) and calculating the Fourier transform at these points.
Method 2: Search on an orthogonal grid but only calculate Fourier transform values for points which are within 1.5 grid units of a given cell vector length.
As the required parts of the Fourier transforms a very sparse for both methods, a simple Fourier transform calculation is done (but using integer arithmetic) rather than using a Fast Fourier Transform.

ang_tol

The maximum difference in degrees from an input cell angle to consider as a reasonable match e.g. 2.0 degrees.

progress

Progress handler (may be null if not required)

Method Return:

Returns an array of JdlSettingSolution objects containing details of possible solutions for the setting. If none are found a null is returned.