decimal in python

1Decimal is a python library that allows for more precise decimals, without a 
2large amount of floating point errors.
3from decimal import *
4getcontext().prec = n
5The above line let''s you change the precision of the decimal.
6i.e.
7getcontext().prec = 6
8print(Decimal(1) / Decimal(7))
9Decimal('0.142857')
10You can see that it has 6 digits of prescision.
11There are useful functions, 
12.log10
13.sqrt
14.exp
15.ln
16First, Decimal(x).log10 returns log10(x).
17I.e.
18print(Decimal(100).log10)
192
20Then, Decimal(x).sqrt returns the square root of a number (duh).
21Returns the square root of a number
22getcontext().prec = 28
23Decimal(2).sqrt()
24Decimal('1.414213562373095048801688724')
25Then .exp is the natural anti-lograthm (natural lograthm is loge(x), where is
26e is Euler''s (say Oiler''s) constant, or 2.718...
27Since exponentiation is the opposite of lograthms,
28Decimal(x).exp = e**x
29getcontext().prec = 3
30Decimal(1).exp()
31Decimal('2.718')
32Finally, .ln is the natural lograthm, or loge(x) .
33For more info check out 
34https://docs.python.org/3/library/decimal.html
35.

1x = 13.949999999999999999
2g = float("{:.2f}".format(x))

1>>> from decimal import *
2>>> getcontext().prec = 6
3>>> Decimal(1) / Decimal(7)
4Decimal('0.142857')
5>>> getcontext().prec = 28
6>>> Decimal(1) / Decimal(7)
7Decimal('0.1428571428571428571428571429')
8