#
#    Copyright (C) 2011 Brendon J. Brewer
#    This file is part of DNest, the Diffusive Nested Sampler.
#
#    DNest is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    DNest is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#    along with DNest.  If not, see <http://www.gnu.org/licenses/>.

import numpy
from numpy import *

def logsumexp(values):
	biggest = max(values)
	x = values - biggest
	result = log(sum(exp(x))) + biggest
	return result

def logdiffexp(x1, x2):
	biggest = x1
	xx1 = x1 - biggest
	xx2 = x2 - biggest
	result = log(exp(xx1) - exp(xx2)) + biggest
	return result