[R] increase thr range in R
Earl F. Glynn
efg at stowers-institute.org
Tue Dec 14 17:00:25 CET 2004
IEEE floating point provides a "double-extended" type often called a long
double. The exact size of a double-extended can vary but the minimum
specified by the spec is 80 bits. A PC with the IEEE extended type gives an
approximate range from 3.4E-4932 to 1.1E4932, which would give you the range
you want. Other architectures, such as a Tru64 alpha, give an even larger
Reference: See the "IEEE Standard" in
"What Every Computer Scientist Should Know About Floating-Point Arithmetic"
The "note" under R's ?numeric help says "All real numbers are stored in
double precision format," so R apparently does not yet support the extended
str(.Machine) in R gives a sizeof.longdouble, but I don't know how to use
such a longdouble in native R -- perhaps someone else could enlighten us. C
or C++ (or other languges) would support the long double type and the
computations you'd like to do.
Earl F. Glynn
Stowers Institute for Medical Research
"Sebastian Kaiser" <KINGSEBI at gmx.net> wrote in message
news:26416.1103030099 at www35.gmx.net...
Hello Everybody in order to get some needed results out of my function i
need to get my besselI function evaluated at some values which normally gave
Inf or 0 (expon.scaled NAN) back. So I would like to increase the range in R
from approxamittly 1e+320 to aabout 1e+500 or something like that. Is there
any possibility or pacckage to do this easily?
Institut for Statistics in Munich Germany
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