data = np.loadtxt("precession_GR.dat")
convert = 3600*180/np.pi

alength = len(data[:,0])
x = data[:,0]
y = data[:,1]
t = np.linspace(0, 100, alength)

arcsecs = np.zeros(alength)
for i in range(alength):
    arcsecs[i] = np.arctan(y[i]/x[i])*convert


p = np.polyfit(t, arcsecs, 1)

b = p[0]
m = p[1]
yline = np.polyval(p, t)
print yline[-1] - yline[0]


plt.plot(t, arcsecs)
plt.plot(t, yline)
plt.xlabel("Time [years]")
plt.ylabel("Seconds of arc")
plt.legend(["Data points", "Fitted line"])
plt.show()