Convert decimal number to character vector representing base N number
str = dec2base(d, base)
str = dec2base(d, base, n)
str = dec2base(d, base) converts
the nonnegative integer d to the specified base. d must
be a nonnegative integer smaller than the value returned by flintmax,
and base must be an integer between 2 and 36. The
returned argument str is a character vector.
str = dec2base(d, base, n) produces
a representation with at least n digits.
The expression dec2base(23, 2) converts 2310 to
base 2, returning the character vector '10111'.