python执行精确的小数计算方法

a = 4.1
b = 5.329
print(a+b)
 
9.428999999999998

from decimal import Decimal
a = Decimal('4.1')
b = Decimal('5.329')
print(a+b)
 
9.429

from decimal import Decimal
from decimal import localcontext
a = Decimal(4.1)
b = Decimal(5.329)
print(a/b)
print('================')
with localcontext() as ctx:
  ctx.prec = 3
  print(a/b)
 
0.7693751172827922400071261708
================
0.769

from decimal import Decimal, getcontext
a = Decimal(4.1)
b = Decimal(5.329)
getcontext().prec = 3
print(a/b)
 
0.769

nums = [3.21e+18, 1, -3.21e+18]
print(sum(nums))
print('=========================')
import math
res = math.fsum(nums)
print(res)
 
0.0
=========================
1.0