NAME:
	meanerr
 PURPOSE: (one line)
	Calculate the mean and estimated errors for a set of data points
 DESCRIPTION:
	This routine is adapted from Program 5-1, XFIT, from "Data Reduction
	and Error Analysis for the Physical Sciences", p. 76, by Philip R.
	Bevington, McGraw Hill.  This routine computes the weighted mean using
	Instrumental weights (w=1/sigma^2).
 CATEGORY:
	Statistics
 CALLING SEQUENCE:
	meanerr,x,sigmax,xmean,sigmam,sigmad
 INPUTS:
	x      - Array of data points
	sigmax - array of standard deviations for data points
 OPTIONAL INPUT PARAMETERS:
	None.
 KEYWORD PARAMETERS:
	None.
 OUTPUTS:
	xmean  - weighted mean
	sigmam - standard deviation of mean
	sigmad - standard deviation of data
 COMMON BLOCKS:
	None.
 SIDE EFFECTS:
	None.
 RESTRICTIONS:
	None.
 PROCEDURE:
 MODIFICATION HISTORY:
	Written by Marc W. Buie, Lowell Observatory, 1992 Feb 20