#!/usr/bin/python -Wall

# ================================================================
# John Kerl
# 2007-06-28
# kerl.john.r@gmail.com
# ================================================================
# This software is released under the terms of the GNU GPL.
# Please see LICENSE.txt in the same directory as this file.
# ================================================================

from __future__ import division # 1/2 = 0.5, not 0.
import sys
import sackmat_m
import stats_m

argc = len(sys.argv)
if ((argc != 2) and (argc != 3)):
	print >> sys.stderr, "Usage: %s {x file name} {y file name}" % (sys.argv[0])
	print >> sys.stderr, "Or:    %s {x-y-pair file name}." % (sys.argv[0])
	print >> sys.stderr, "Use \"-\" as file name for stdin."
	sys.exit(1)

if (argc == 3):
	file_name_1 = sys.argv[1]
	file_name_2 = sys.argv[2]

	xs = sackmat_m.read_column_vector(float, file_name_1)
	ys = sackmat_m.read_column_vector(float, file_name_2)
elif (argc == 2):
	file_name = sys.argv[1]
	xys = sackmat_m.read_matrix(float, file_name)
	xs = xys.get_column(0)
	ys = xys.get_column(1)

covar = stats_m.find_sample_covariance(xs, ys)
print covar