shaoziyang 发表于1年前

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``````"""

2016.5
v1.1
http://bbs.micro-python.com/forum.php
"""
import time

def pi(places=10):
# 3 + 3*(1/24) + 3*(1/24)*(9/80) + 3*(1/24)*(9/80)*(25/168)
# The numerators 1, 9, 25, ... are given by (2x + 1) ^ 2
# The denominators 24, 80, 168 are given by (16x^2 -24x + 8)
extra = 8
one = 10 ** (places+extra)
t, c, n, na, d, da = 3*one, 3*one, 1, 0, 0, 24

while t > 1:
n, na, d, da = n+na, na+8, d+da, da+32
t = t * n // d
c += t
return c // (10 ** extra)

def pi_t(n=10):
t1=time.ticks_us()
t=pi(n)
t2=time.ticks_us()
print('elapsed: ', time.ticks_diff(t1,t2)/1000000, 's')
return t

def pi2(n=10):
r=6*(10**n)*1000
p=0
k=0
c=r//2
d=c//(2*k+1)
while d>0:
p=p+d
k=k+1
k2=2*k
c=c*(k2-1)//(4*k2)
d=c//(k2+1)
return p//1000

def pi2_t(n=10):
t1=time.ticks_us()
t=pi2(n)
t2=time.ticks_us()
print('elapsed: ', time.ticks_diff(t1,t2)/1000000, 's')
return t
``````

MicroPython v1.8 on 2016-05-15; F7DISC with STM32F746
>>> import pi
>>> npi=pi.pi_t(1000)
elapsed:  0.221486 s
>>> npi=pi.pi_t(2000)
elapsed:  0.793141 s
>>> npi=pi.pi_t(5000)
elapsed:  4.981964 s
>>> npi=pi.pi_t(10000)
elapsed:  21.02012 s
>>>

>>> pi.pi(1000)
31415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989
>>>

pi2方法是干嘛的？

pi2方法是干嘛的？

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