• NAME
• PARAMETERS
• DESCRIPTION
• AUTHOR

NAME

centroid - determine the centroid of a ray file (and other things)

PARAMETERS

centroid uses the standard parameter interface

input file

The input ray stream. If it's the string stdin, the rays are read from UNIX standard input. Rays must be in bpipe format.

output filename

This specifies the output file for the rays (they just get copied through). If it's the string stdout, the rays are sent to the UNIX standard output stream. Rays are written in bpipe format.

output filename

This specifies where the results are written. If it's the string stderr, the rays are sent to the UNIX standard output stream. If it's the string stdout, the rays are sent to the UNIX standard output stream.

clip boolean

If true, the rays are clipped to the radius specified by the radius parameter.

xcent float =item ycent float

The coordinatew of the center about which to measure the centroid.

radius float

The radius of the clipping circle, if clip is true.

help boolean

Print out some help.

version boolean

Print out centroid's version and exit.

debug list

A list of debug flags. None are presently defined.

DESCRIPTION

centroid calculates a bunch of statistics for the ray stream, and outputs an rdb table with the results.

The quantities calculated, and the name of the resultant output columns are:

• mean position ( x_ave, y_ave, z_ave )
• standard deviation ( x_dev, y_dev, z_dev )
• RMS position ( x_rms , y_rms, z_rms )
• RMS radius ( r_rms )

  This is the RMS radius about the given center. If the RMS radius about the mean position is required, you'll have to run this puppy twice.

The mean, standard deviation, and RMS position calculations are done according to ``Updating Mean and Variance Estimates: An Improved Method'', D.H.D. West, Communications of the ACM, 22:532, 197. The RMS radius is done the ol' grungy way.

AUTHOR

D. Jerius