Verify sum of three cubes equal to 33: fails in R, works in Python

Question

Newly, there was a solution found for the following equation in integers:

x^3 + y^3 + z^3 = 33

Namely, it holds for x = 8866128975287528, y= -8778405442862239, and z=-2736111468807040

If I check it in Python, it's fine:

>>> (8866128975287528)**3 - (8778405442862239)**3 - (2736111468807040)**3
33L

However, in R it doesn't work:

8866128975287528^3 - 8778405442862239^3 - 2736111468807040^3
[1] -2.535301e+30

Why?

Python uses unlimited precision integers, whereas R uses 32bit integers. — juanpa.arrivillaga, Apr 01 '19 at 20:49
It shows no warning because it probably interprets those literals as doubles. — Jan Christoph Terasa, Apr 01 '19 at 21:21

J_F · Accepted Answer · 2019-04-01T21:17:21.183

4

The biggest number with 32 bit is 2,147,483,647. You have to use special libraries. You can use the library(opennssl) with the function bignum().

library(openssl)
bignum(8866128975287528)^3 - bignum(8778405442862239)^3 - bignum(2736111468807040)^3

> 33

edited Apr 01 '19 at 21:17

answered Apr 01 '19 at 20:41

J_F

9,956
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31
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score 2 · Answer 2 · answered Apr 01 '19 at 20:33

2

R uses 32-bit integers, which means the largest integer R can hold is around 2 billion. You can use the package int64 to try to get around this. See this question for more information.

answered Apr 01 '19 at 20:33

Nathaniel

3,230
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Verify sum of three cubes equal to 33: fails in R, works in Python

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