R Developers, 1000000000000000000 %% 11 [1] -32 I now understand that integers cannot be larger than .Machine$integer.max, but because the above produces a result than is patently wrong instead of an error, I'm reporting this as a bug. Thank you for the incredible contributions all of you have made in developing the R platform. Best, Robert Robert McGehee Geode Capital Management, LLC 53 State Street, 5th Floor | Boston, MA | 02109 Tel: 617/392-8396 Fax:617/476-6389 mailto:robert.mcgehee@geodecapital.com This e-mail, and any attachments hereto, are intended for use by the addressee(s) only and may contain information that is (i) confidential information of Geode Capital Management, LLC and/or its affiliates, and/or (ii) proprietary information of Geode Capital Management, LLC and/or its affiliates. If you are not the intended recipient of this e-mail, or if you have otherwise received this e-mail in error, please immediately notify me by telephone (you may call collect), or by e-mail, and please permanently delete the original, any print outs and any copies of the foregoing. Any dissemination, distribution or copying of this e-mail is strictly prohibited.
This is nothing to do with integers: 1e18 and 11 are doubles here.
It is a result of rounding error: 1e18/11 is not representable accurately,
and this should have been a warning to you that your calculations were
unreasonable.
The C code is
double myfmod(double x1, double x2)
{
double q = x1 / x2;
return x1 - floor(q) * x2;
}
We can improve the answer, but what you are doing is fundamentally flawed
and it is hard to detect whether rounding error has affected this. A
warning rather than an error seems appropriate.
If you really want to do things like this, try the gmp package (which
seems to give the wrong answer here) or a more appropriate calculator.
On Thu, 9 Dec 2004 Robert.McGehee@geodecapital.com wrote:
> R Developers,
>
> 1000000000000000000 %% 11
> [1] -32
>
> I now understand that integers cannot be larger than
> .Machine$integer.max, but because the above produces a result than is
> patently wrong instead of an error, I'm reporting this as a bug.
--
Brian D. Ripley, ripley@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595