Constants {base} | R Documentation

## Built-in Constants

### Description

Constants built into R.

### Usage

    LETTERS
    letters
    month.abb
    month.name
    pi

### Details

R has a limited number of built-in constants (there is also a rather larger library of data sets which can be loaded with the function `data`).

The following constants are available:

- `LETTERS`: the 26 upper-case letters of the Roman alphabet;
- `letters`: the 26 lower-case letters of the Roman alphabet;
- `month.abb`: the three-letter abbreviations for the English month names;
- `month.name`: the English names for the months of the year;
- `pi`: the ratio of the circumference of a circle to its diameter.

### See Also

`data`.

### Examples

    stopifnot(
     nchar(letters) == 1,
     month.abb == substr(month.name, 1, 3)
    )
    eps <- .Machine$double.eps
    all.equal(pi, 4*atan(1), tol= 2*eps)

    # John Machin (1705) computed 100 decimals of pi :
    all.equal(pi/4, 4*atan(1/5) - atan(1/239), 4*eps)

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