Roman

Parses or formats Roman numerals.

Syntax

• Roman(n)

  • n is an integer

• Roman(s)

  • s is a string

Description

If n is an integer, then Roman(n) returns n formatted as a Roman numeral.

If s is a string containing a Roman numeral representation of an integer, then Roman(s) returns this integer; that is, Roman(s) parses s as a Roman numeral.

If n is an integer, Roman(n) is equivalent to SetFormatStyle(n, "Roman").

Examples

Roman(1987)

MCMLXXXVII

Roman("MCMLXXXVII")

1987

Notes

The integer 0 is formatted as N in Roman numerals:

Roman(0)

N

Roman("N")

0

Negative values are prefixed with a minus sign in Roman numerals:

Roman(−520)

−DXX

However, the minus sign is not allowed when parsing strings as Roman numerals.

In Roman numerals, large numbers are written in groups separated by hyphens. Read from right to left, each hyphen signals an additional factor of one thousand:

Roman(299792458)

CCXCIX'DCCXC'MMCDLVIII

This should be parsed as

 MMCDLVIII + 10³⋅DCCXC + 10⁶⋅CCXCIX

And, indeed,

Roman("CCXCIX'DCCXC'MMCDLVIII")

299792458

The parser is forgiving and accepts non-standard Roman numerals, as long as they are unambiguous. For example,

'( "MCMLXXXVII", "LMMXXXVII", "XXMMVII", "XXMMIIIIIII", 1987⋅"I" ) @ Roman

1987  1987  1987  1987  1987

where the last string in the list literally consists of the character I repeated 1987 times.

See also

• FormatStyle

• SetFormatStyle