ceiling takes a single numeric argument x and returns a
numeric vector containing the smallest integers not less than the
corresponding elements of x. floor takes a single numeric argument x and returns a
numeric vector containing the largest integers not greater than the
corresponding elements of x.
trunc takes a single numeric argument x and returns a
numeric vector containing the integers formed by truncating the values in
x toward 0.
round rounds the values in its first argument to the specified
number of decimal places (default 0).
signif rounds the values in its first argument to the specified
number of significant digits.
ceiling(x)
floor(x)
trunc(x, ...)
round(x, digits = 0)
signif(x, digits = 6)round and signif, a
complex vector.round) or significant digits (signif) to be used.
Negative values are allowed (see ‘Details’).ceiling, floor and trunc are members of the
Math group generic. As an S4
generic, trunc has only one argument. round and signif are members of the
Math2 group generic.floor and ceiling. For example, we
‘know’ that floor(log(x, base = 8)) for x = 8 is
1, but 0 has been seen on an R platform. It is
normally necessary to use a tolerance.Math group
generic. Note that for rounding off a 5, the IEC 60559 standard is expected to
be used, ‘go to the even digit’.
Therefore round(0.5) is 0 and round(-1.5) is
-2. However, this is dependent on OS services and on
representation error (since e.g.\ifelse{latex}{\out{~}}{ } 0.15 is not represented
exactly, the rounding rule applies to the represented number and not
to the printed number, and so round(0.15, 1) could be either
0.1 or 0.2).
Rounding to a negative number of digits means rounding to a power of
ten, so for example round(x, digits = -2) rounds to the nearest
hundred.
For signif the recognized values of digits are
1...22, and non-missing values are rounded to the nearest
integer in that range. Complex numbers are rounded to retain the
specified number of digits in the larger of the components. Each
element of the vector is rounded individually, unlike printing.
These are all primitive functions.
as.integer.
round(.5 + -2:4) # IEEE rounding: -2 0 0 2 2 4 4
( x1 <- seq(-2, 4, by = .5) )
round(x1) #-- IEEE rounding !
x1[trunc(x1) != floor(x1)]
x1[round(x1) != floor(x1 + .5)]
(non.int <- ceiling(x1) != floor(x1))
x2 <- pi * 100^(-1:3)
round(x2, 3)
signif(x2, 3)
Run the code above in your browser using DataLab