python - All decimal places [Python]

Question

I am trying to create an E (mathematical constant) approximation script. But it only gives me 15 decimals places. I then added a Decimal() which increased the number of decimal places but was still limited to 50 decimal places. Is there any way to print all decimals. (If not, what's the limit?)

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Here's my code:

from decimal import *
e=1
x = input("Iterations:")
x=int(x)
while 1==1:
    e=1 + e/x
    x -= 1
    if (x <= 0):
        break

print(Decimal(e)) # only prints 50 decimal places

标签： pythonpython-3.xdecimal

Answer 1

Casting your floating point result to Decimal is, of course, not enough. You have to perform all of the computations using Decimal objects and, if you need a large precision, you have to tell decimal about that

In [73]: from decimal import Decimal, getcontext                                        
In [74]: getcontext().prec = 70                                                         
In [75]: e = Decimal(1)                                                                 
In [76]: x = Decimal(200000)                                                            
In [77]: while x>0: 
    ...:     e = Decimal(1)+e/x 
    ...:     x = x-Decimal(1)                                                           
In [78]: e                                                                              
Out[78]: Decimal('2.718281828459045235360287471352662497757247093699959574966967627724076')
In [79]: str(e)[:52]                                                                    
Out[79]: '2.71828182845904523536028747135266249775724709369995'