how can i show an irrational number to 100 decimal places in python?

问题

I am trying to find the square root of 2 to 100 decimal places, but it only shows to like 10 by default, how can I change this?

回答1:

decimal module comes in handy.

>>> from decimal import *
>>> getcontext().prec = 100
>>> Decimal(2).sqrt()
Decimal('1.414213562373095048801688724209698078569671875376948073176679737990732478462107038850387534327641573')

回答2:

You can use the decimal module for arbitrary precision numbers:

import decimal

d2 = decimal.Decimal(2)

# Add a context with an arbitrary precision of 100
dot100 = decimal.Context(prec=100)

print d2.sqrt(dot100)

If you need the same kind of ability coupled to speed, there are some other options: [gmpy], 2, cdecimal.

回答3:

You can use gmpy2.

import gmpy2
ctx = gmpy2.get_context()
ctx.precision = 300
print(gmpy2.sqrt(2))

回答4:

You can use sympy and evalf()

from sympy import sqrt
print(sqrt(2).evalf(101))

来源：https://stackoverflow.com/questions/4733173/how-can-i-show-an-irrational-number-to-100-decimal-places-in-python