.Machine
is a variable holding information on the numerical
characteristics of the machine R is running on, such as the largest
double or integer and the machine's precision.
.Machine
x
such that 1 + x != 1
. It equals
double.base ^ ulp.digits
if either double.base
is 2 or
double.rounding
is 0; otherwise, it is
(double.base ^ double.ulp.digits) / 2
. Normally
2.220446e-16
.x
such that 1 - x != 1
. It equals
double.base ^ double.neg.ulp.digits
if double.base
is 2
or double.rounding
is 0; otherwise, it is
(double.base ^ double.neg.ulp.digits) / 2
. Normally
1.110223e-16
. As double.neg.ulp.digits
is bounded
below by -(double.digits + 3)
, double.neg.eps
may not
be the smallest number that can alter 1 by subtraction.double.base ^ double.min.exp
. Normally 2.225074e-308
.(1 - double.neg.eps) *
double.base ^ double.max.exp
, but
on some machines it is only the second or third largest such
number, being too small by 1 or 2 units in the last digit of the
significand. Normally 1.797693e+308
. Note that larger
unnormalized numbers can occur.2
.53
.5
.double digits
base-double.base
digits
participate in the post-normalization shift of the floating-point
significand in multiplication, and 0 otherwise.
Normally 0
.i
such
that 1 + double.base ^ i != 1
, except that it is bounded below by
-(double.digits + 3)
. Normally -52
.i
such that 1 - double.base ^ i != 1
, except that it is bounded
below by -(double.digits + 3)
. Normally -53
.double.base
is 10) reserved
for the representation of the exponent (including the bias or sign)
of a floating-point number. Normally 11
.i
such that
double.base ^ i
is positive and normalized. Normally -1022
.double.base
that overflows. Normally
1024
.2147483647
.long
type:
4
or 8
(most 64-bit systems, but not Windows).long long
type. Will be zero if there is no such type, otherwise usually
8
.long double
type. Will be zero if there is no such type (or its use was
disabled when R was built), otherwise possibly
12
(most 32-bit builds) or 16
(most 64-bit builds).SEXP
type. Will be 4
on 32-bit builds and 8
on 64-bit
builds of R. Note that on most platforms smaller positive values than
.Machine$double.xmin
can occur. On a typical R platform the
smallest positive double is about 5e-324
.
.Platform
for details of the platform.
.Machine
## or for a neat printout
noquote(unlist(format(.Machine)))
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