chord

NAME

chord - determines the center of a ring image.

DESCRIPTION

The x and y coordinates of photons are read from an rdb table. Pairs of chords are randomly chosen, and the intersection of their perpendicular bisectors approximates the center of the 'circle.' Only certain combinations of chord pairs are analyzed: only chords whose lengths lies between 1.0 and 2.2 times the approximate radius of the circle are allowed, only chords that are ``not too parallel'' (the angle between the chords must be greater than about 30 degrees) are allowed, and a calculated circle center whose distance from the approximate center is greater than the approximate radius are ignored. The average of the locations of the intersections is the estimated center of the image.

PARAMETERS

block integer
Block to get seed, 0<= Block <=1048575

seed1 integer
Seed #1 for Ranlib

seed2 integer
Seed #2 for Ranlib

numcalc integer
The number of combinations (sets of pairs of chords)

input filename
Filename of rdb table of photons which lie on circle

output filename
Filename of center data: average x coordinate, average y coordinate, standard deviation of x coordinates, standard deviation of y coordinates, number of combinations

version boolean
If equal to yes, print version number then die

verbose boolean
If equal to yes, calculate and print minimum and maximum x and y coordinates, minimum and maximum chord lengths, and approximate radius of circle.

.

AUTHOR

D. Grumm