d< d< d> d= d0< d0= dinvert
D< ( d d -- f )
True if less than.
D> ( d d -- f )
True if greater than.
D= ( d d -- f )
True if equal.
D0< ( d -- f )
True if d is negative.
D0= ( d -- f )
True if d equals zero.
DINVERT ( ud -- ud )
Invert double number.