/*
 *  call-seq:
 *     dvector.reverse_each3_with_index {|x,y,z,index| block }  ->  dvector
 *  
 *  Same as <code>Dvector#each3_with_index</code>, but traverses the vectors in reverse
 *  order.
 *     
 *     a = Dvector[ 1, 0, -1 ]
 *     b = Dvector[ 3, 4, 5 ]
 *     c = Dvector[ 6, 9, 2 ]
 *     a.reverse_each3_with_index(b,c) {|x,y,i| print "(", x ",", y, "," i, ") " }
 *     a.each3(b, c) {|x,y,z,i| print "(", x ",", y, ", ", z, ",", i, ") " }
 *     
 *  produces:
 *     
 *      (-1,5,2,2) (0,4,9,1) (1,3,6,0)
 */ VALUE dvector_reverse_each3_with_index(VALUE ary, VALUE ary2, VALUE ary3) {