/*
 *  call-seq:
 *     dvector.modulo(number)       ->  a_dvector
 *     dvector.mod(number)          ->  a_dvector
 *     dvector.modulo(other)        ->  a_dvector
 *     dvector.mod(other)           ->  a_dvector
 *     dvector % number             ->  a_dvector
 *     dvector % other              ->  a_dvector
 *  
 *  When argument is a number, this operation returns a copy of _dvector_ with each entry x replaced by x % _number_.
 *  When argument is a vector, this operation returns a copy of _dvector_ with each entry x replaced
 *  by x % the corresponding entry in the _other_ vector.
 *     
 *     a = Dvector[ 1.1, -5.7, 12.7 ]
 *     a.mod(3.8)              -> Dvector[ 1.1, 1.9, 1.3 ]
 *     a % 3.8                 -> Dvector[ 1.1, 1.9, 1.3 ]
 *     b = Dvector[ 7.1, 4.9, -10.1 ]
 *     a.mod(b)                -> Dvector[ 1.1, 4.1, -7.5 ]
 *     a % b                   -> Dvector[ 1.1, 4.1, -7.5 ]
 */ 
VALUE dvector_mod(VALUE ary, VALUE arg) {