#
#
#			created by Richard Ignace
#			    February 14, 1993
#
#
#	The script take the first two columns of a stream and outputs
#	some basic statistics:  a mean, min, max, std. dev., m, and b.
#	The standard deviation is:
#
#			sigma = sqrt (variance)
#
#			                      sum(y)^2
#				sum(y^2) -  --------
#					        N
#		variance   =    ---------------------
#					N-1
#

BEGIN {
   sumx = 0
   sumy = 0
   sumxsq = 0
   sumysq = 0
   sumxy = 0
   }
   {

   x = $1
   y = $2
   if (NR == 1) {
      min = y
      max = y
   }

   if (y < min) {
      min = y }
   else if (y > max) {
      max = y }

   sumx += x
   sumxsq += x*x
   sumy += y
   sumysq += y*y
   sumxy += x*y

   }
END {

   meanx = sumx/NR
   meany = sumy/NR
   sigmay = sqrt( sumysq - sumy*sumy/NR )/sqrt(NR-1)
   m = (sumx*sumy-NR*sumxy)/(sumx*sumx-NR*sumxsq)
   b = (sumx*sumxy-sumy*sumxsq)/(sumx*sumx-NR*sumxsq)

   printf "%.3e\t%.3e\t%.3e\t%.3e\t%.3e\t%.3e\t%d\n", meany, min, max, sigmay, m, b, NR

}
