program displaying to few digits

Question

This program computes the square root of 2, but it will not display the digits to my desired accuracy of 1000 digits, but instead it only displays 50 digits.

here is the program

import math 
a=format(2.0**0.5, '.1000')   
print a

I would like to know how to write a program to display more digits.

Answer 1

Use the decimal module:

>>> from decimal import *
>>> getcontext().prec = 100
>>> Decimal(2).sqrt()
Decimal('1.414213562373095048801688724209698078569671875376948073176679737990732478462107038850387534327641573')
>>> getcontext().prec = 1000
>>> Decimal(2).sqrt()
Decimal('1.4142135623730950488016887242096980785696718753769480731766797379907324784621070388503875343276415727350138462309122970249248360558507372126
441214970999358314132226659275055927557999505011527820605714701095599716059702745345968620147285174186408891986095523292304843087143214508397626036279
952514079896872533965463318088296406206152583523950547457502877599617298355752203375318570113543746034084988471603868999706990048150305440277903164542
478230684929369186215805784631115966687130130156185689872372352885092648612494977154218334204285686060146824720771435854874155657069677653720226485447
015858801620758474922657226002085584466521458398893944370926591800311388246468157082630100594858704003186480342194897278290641045072636881313739855256
117322040245091227700226941127573627280495738108967504018369868368450725799364729060762996941380475654823728997180326802474420629269124859052181004459
84215059112024944134172853147810580360337107730918286931471017111168391658172688941975871658215212822951848847')