#! /bin/bash
#
# cor - Read pairs from std-in, one per line, and write to std-out the
#   correlation of the points.

gawk '{ if (NF != 2) {
	  print "Input should have 2 fields, not " NF "." > "/dev/stderr"
	  exit 1
	  }

	sum_x += $1
        sum_y += $2
	sum_xy += $1*$2
	sum_xsq += $1*$1
	sum_ysq += $2*$2
	}

      END {
	if (NR > 0) {
          n = NR*sum_xy - sum_x*sum_y
	  d = (NR*sum_xsq - sum_x*sum_x)*(NR*sum_ysq - sum_y*sum_y)
	  print n/sqrt(d)
	  }
	else
	  print 0
        }
     '

# $Log: cor,v $
# Revision 1.1  2005/04/04 03:07:29  rclayton
# Created.
#