# this program test stability of computing power of golden mean
# phi**n, phi =(sqrt(5.)-1.0)/2.0
#
# Since default setting for float in Python is double precision,
# we must work harder to show this instability (i.e. run upto i = 59).
#
import math

p0 = 0.5*(math.sqrt(5.0)-1.0)

p = 1.0
f0 = 1.0
f1 = p0

for i in range(0,60):
    print("i=",i, "phi**i by mul=", p, "by **=", p0**i, "by sub=", f0)
    p = p*p0
    f2 = f0-f1
    f0 = f1
    f1 = f2

print("the end")