Hello Dear all
I tried understand :
import math
n=115792089237316195423570985008687907852837564279074904382605163141518161494337
d= math.sqrt(n)
print(d)
print(d==2**128)
print(d*d==n)
u=d*d
print(u)
print(n-u)
result: how it is possibility that sqrt(n) *sqrt(n) is equal n if it is not?:)
Your n is not the square of 2^128:
sage: n=115792089237316195423570985008687907852837564279074904382605163141518161494337
sage: (2^128)^2 - n
432420386565659656852420866394968145599
But, if you use float, then the precision of floats (53 bits of precision) is not enough to see a difference:
sage: float((2^128)^2) - float(n)
0.0
So, don't use float and don't use math.sqrt which returns float to compute such equalities or differences:
sage: type(math.sqrt(n))
<class 'float'>
Asked: 2021-07-12 12:36:41 +0100
Seen: 240 times
Last updated: Jul 12 '21
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