R is probably not the best tool for handling large integers... AFAIK Python has the interesting feature of not only having a `long' integer type (that can store arbitrarily large integers), but can convert a regular 4-byte int to the `long' type when necessary. Perhaps that would be a better tool for the purpose.
Andy From: jim holtman > > 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 <[EMAIL PROTECTED]> 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 > > > > ______________________________________________ > > [email protected] 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]] > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
