#!/usr/bin/python

from pylab import *

y, x = loadtxt("FeAl28-sample1-2.XLS",usecols=(2,3),unpack=True)[:,5:-2]
x = -x

plot(x,y)

data =  array(ginput(2))

a,b = polyfit(data[:,0], data[:,1], 1)

plot(x,a*(x+b/a))

figure()
plot(x+b/a-y/a, y)

show()