SAMPLE

Introduction

SAMPLE is a program for performing Fourier-Bessel smoothing on continuous layer line data as output by LSQINT, using the formula described by Makowski (1982). The data are fitted using singular value decomposition to give intensity values at the specified number of knot points.

Input

The input file data is read from ASCII intensity files output by LSQINT.

Keywords

Keyworded input can be either upper or lower case. Only the first four characters of the keyword are required (and read). When values are input, they can take integer, real or exponent fields. Comments are signalled by ! and can occur anywhere on a line. Up to five continuation lines are allowed using & at the end of the current line. Lines must be less than 132 characters. Descriptions of the keywords recognised by CONV are given below.
(Sub-keywords are indented on the line following the main keyword)

FILE - SAMPLE will then prompt for the input file name

RESOlution - two values to follow, the minimum and maximum resolution in reciprocal angstroems
(Defaults: d* minimum = 0.0, d* maximum = maximum resolution in dataset)

SIGMA - one value to follow, the minimum ratio of I/sigma(I) for I to be included in the fit
(Default: SIGMA = 0.0)

EXTRa - one value to follow, the number of roots past the maximum reciprocal radius on a layer line to be used in fitting the data
Default: EXTRA = 5)

HELIx - two values to follow, the number of subunits and the number of turns defining the helical symmetry
(Default: SUBUNITS = 1, TURNS = 1)

STARt - one value to follow, the rotational symmetry of the structure.
(Default: START = 1)

STACk - one value to follow, the number of stacked helices.
(Default: STACK = 1)

RADIus - one value to follow, the maximum radius of the structure. (Default: RADIUS = 100.0A) SCALe - one value to follow, the scale factor relating the actual layer line numbers to those recorded in the LSQINT output file i.e. Lactual = Llsqint * SCALE
(Default: SCALE = 1)

RUN - Start smoothing

Output

The output file is in the same format as the LSQINT output file.

Reference

Makowski, L. (1982). J. Appl. Cryst. 15 546-557