These are generic functions: methods can be defined for them
individually or via the `Math`

group
generic.

Note that for rounding off a 5, the IEC 60559 standard (see also
‘IEEE 754’) 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.`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.