From: jim holtman <jholtman_at_gmail.com>

Date: Tue 31 Jan 2006 - 04:54:25 EST

*>
*

*> 8^35
*

[1] 4.056482e+31

*> 8^36
*

[1] 3.245186e+32

*> 8^19
*

[1] 1.441152e+17

*> 8^19%%41
*

[1] 36

*> 8^20
*

[1] 1.152922e+18

*> 8^20%%41
*

[1] 1

Warning message:

probable complete loss of accuracy in modulus

*>
*

Date: Tue 31 Jan 2006 - 04:54:25 EST

> a=1:40;

*> 8^a %% 41
*

[1] 8 23 20 37 9 31 2 16 5 40 33 18 21 4 32 10 39 25 36 1 8 23 20
37 9 31 2 16 5 40 33

[32] 18 21 4 32 10 0 0 0 0

There were 21 warnings (use warnings() to see them)

*> warnings()
*

Warning messages:

1: probable complete loss of accuracy in modulus 2: probable complete loss of accuracy in modulus 3: probable complete loss of accuracy in modulus 4: probable complete loss of accuracy in modulus 5: probable complete loss of accuracy in modulus 6: probable complete loss of accuracy in modulus 7: probable complete loss of accuracy in modulus 8: probable complete loss of accuracy in modulus 9: probable complete loss of accuracy in modulus 10: probable complete loss of accuracy in modulus 11: probable complete loss of accuracy in modulus 12: probable complete loss of accuracy in modulus 13: probable complete loss of accuracy in modulus 14: probable complete loss of accuracy in modulus 15: probable complete loss of accuracy in modulus 16: probable complete loss of accuracy in modulus 17: probable complete loss of accuracy in modulus 18: probable complete loss of accuracy in modulus 19: probable complete loss of accuracy in modulus20: probable complete loss of accuracy in modulus 21: probable complete loss of accuracy in modulus

[1] 4.056482e+31

[1] 3.245186e+32

[1] 1.441152e+17

[1] 36

[1] 1.152922e+18

[1] 1

Warning message:

probable complete loss of accuracy in modulus

On 1/30/06, Ionut Florescu <ifloresc@stevens.edu> wrote:

*>
*

> I am a statistician and I come up to an interesting problem in

*> cryptography. I would like to use R since there are some statistical
**> procedures that I need to use.
**> However, I run into a problem when using the modulus operator %%.
**>
**> I am using R 2.2.1 and when I calculate modulus for large numbers (that
**> I need with my problem) R gives me warnings. For instance if one does:
**> a=1:40;
**> 8^a %% 41
**> one obtains zeros which is not possible since 8 to any power is not a
**> multiple of 41.
**> In addition when working with numbers larger that this and with the mod
**> operator R crashes randomly.
**>
**> I believe this is because R stores large integers as real numbers thus
**> there may be lack of accuracy when applying the modulus operator and
**> converting back to integers.
**>
**> So my question is this: Is it possible to increase the size of memory
**> used for storing integers? Say from 32 bits to 512 bits (Typical size of
**> integers in cryptography).
**>
**> Thank you, any help would be greatly appreciated.
**> Ionut Florescu
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
**>
*

-- Jim Holtman Cincinnati, OH +1 513 247 0281 What the problem you are trying to solve? [[alternative HTML version deleted]] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.htmlReceived on Tue Jan 31 05:07:29 2006

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