FUNCTION: BnGenCode - generate one code

CALLING SEQUENCE:

BnGenCode(n, typecode)

BnGenCode(code, typecode)

BN[BnGenCode](n, typecode)

BN[BnGenCode](code, typecode)

PARAMETERS:

n = any positive integer

code = any list denoting a code

typecode = 'first', 'previous', 'next', 'last'

SYNOPSIS:

• The BnGenCode function generates one element of a hyperoctahedral group in lexicographic order, according to the parameter typecode.

• BnGenCode(n, 'first') returns the first code of B(n).

• BnGenCode(n, 'last') returns the last code of B(n).

• BnGenCode(code, 'previous') gives the previous code according to the lexicographic order. It returns the NULL value when code is already the first code [0, 0, 0, ...].

• BnGenCode(code, 'next') gives the next code according to the lexicographic order. It returns the NULL value when code is already the last code [1, 3, 5, ...].

• Whenever there is a conflict between the function name BnGenCode and another name used in the same session, use the long form BN['BnGenCode'].

EXAMPLES:

> with(BN):
> BnGenCode([1, 2, 5, 7], 'next');
 
                                [1, 3, 0, 0]
 
> BnGenCode([1, 3, 0, 0], 'previous');
 
                                [1, 2, 5, 7]