R is probably not the best tool for handling large integers...

4-byte int to the `long' type when necessary. Perhaps that would be a

better tool for the purpose.

>

> You have reached the maximum value that can be stored accurately in a

> floating point number. That is what the error message is

> telling you. I

> get 21 warnings and this says that at 8^20 I am now

> truncating digits in the

> variable. You only have about 54 bits in the floating point

> number and you

> exceed this about 8^19.

>

> > 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 modulus

> 20: probable complete loss of accuracy in modulus

> 21: probable complete loss of accuracy in modulus

> >

> > 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

> >

>

>

>

> On 1/30/06, Ionut Florescu <

[hidden email]> 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

> >

> > ______________________________________________

> >

[hidden email] 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]]

>

> ______________________________________________

>

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>

https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide!

>

http://www.R-project.org/posting-guide.html>

>