/*
 *  call-seq:
 *     dvector.reverse_each2(other) {|x,y| block } 
 *  
 *  Same as <code>Dvector#each2</code>, but traverses vectors in reverse
 *  order.  The vectors must have the same size.
 *     
 *     a = Dvector[ 1, 0, -1 ]
 *     b = Dvector[ 3, 4, 5 ]
 *     a.reverse_each2(b) {|x,y| print "(", x ",", y, ") " }
 *     
 *  produces:
 *     
 *      (-1,5) (0,4) (1,3)
 */ VALUE dvector_reverse_each2(VALUE ary, VALUE ary2) {