/* 
 *  call-seq:
 *     dvector <=> other   ->  -1, 0, +1
 *
 *  Comparison---Returns an integer (-1, 0,
 *  or +1) if this vector is less than, equal to, or greater than
 *  _other_.  Two vectors are
 *  ``equal'' according to <code>Dvector#<=></code> if and only if they have
 *  the same length and contain exactly the same values.
 *  
 *  
 *     Dvector[ 1, 1, 2 ] <=> Dvector[ 1, 2, 3 ]        -> -1
 *     Dvector[ 1, 1, 2 ] <=> Dvector[ 1, 0, 3 ]        -> +1
 *     Dvector[ 1, 1, 2 ] <=> Dvector[ 1, 1, 2, 3 ]     -> -1
 *     Dvector[ 1, 2, 3, 4, 5, 6 ] <=> Dvector[ 1, 2 ]  -> +1
 *
 */ 
VALUE dvector_cmp(VALUE ary1, VALUE ary2) {