def eliminate_error(n, s):
"""Eliminate error term of given asymptotic order n.
The stream s must be based on halving h at each step
for the formula used here to work."""
while True:
a, b, s = unpack(2, s, k=1)
yield (b * 2**n - a) / (2**(n - 1))
def len_gt(k, s):
# see also unpythonic.slicing.islice; could implement as return islice(s)[k + 1]
a, _ = unpack(1, drop(k, s))
return a # None if no item
def euler_transform(s):
while True:
a, b, c, s = unpack(3, s, k=1)
yield c - ((c - b)**2 / (a - 2 * b + c))
def order(s):
"""Estimate asymptotic order of s, consuming the first three terms."""
a, b, c, _ = unpack(3, s)
return round(log2(abs((a - c) / (b - c)) - 1))
def within(eps, s): # in real code, prefer unpythonic.it.within
while True:
# unpack with peek (but be careful, the rewinded tail is a tee'd copy)
a, b, s = unpack(2, s, k=1)
if abs(a - b) < eps:
return b
def len_gt(k, s):
a, _ = unpack(1, drop(k, s))
return a # None if no item
def within(eps, s):
while True:
# unpack with peek (but be careful, the rewinded tail is a tee'd copy)
a, b, s = unpack(2, s, k=1)
if abs(a - b) < eps:
return b