R: Rounding of Numbers

Round {base} | R Documentation

## Rounding of Numbers

### Description

`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`.

`round` rounds the values in its first argument to the specified number of decimal places (default 0). Note that for rounding off a 5, the IEEE standard is used, “go to the even digit”. Therefore `round(0.5)` is `0` and `round(-1.5)` is `-2`.

`signif` rounds the values in its first argument to the specified number of significant digits.

`trunc` takes a single numeric argument `x` and returns a numeric vector containing the integers by truncating the values in `x` toward `0`.

`zapsmall` determines a `digits` argument `dr` for calling `round(x, digits = dr)` such that values “close to zero” (compared with the maximal absolute one) are “zapped”, i.e., treated as `0`.

### Usage

    ceiling(x)
    floor(x)
    round(x, digits = 0)
    signif(x, digits = 6)
    trunc(x)
    zapsmall(x, digits= getOption("digits"))

### Arguments

`x` | a numeric vector.
`digits` | integer indicating the precision to be used.

### Details

All but `zapsmall` are generic functions: methods can be defined for them individually or via the `Math` group generic.

### References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole. (except `zapsmall`.)

Chambers, J. M. (1998) Programming with Data. A Guide to the S Language. Springer. (`zapsmall`.)

### See Also

`as.integer`.

### Examples

    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)

    print   (x2 / 1000, digits=4)
    zapsmall(x2 / 1000, digits=4)
    zapsmall(exp(1i*0:4*pi/2))

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