/* * call-seq: * dvector.first -> number or nil * dvector.first(count) -> a_dvector * * Returns the first element, or the first _count_ elements, of _dvector_. If the vector is empty, * the first form returns <code>nil</code>, and the second returns an empty vector. * * a = Dvector[ 1, 2, 3, 4, 5 ] * a.first -> 1 * a.first(1) -> Dvector[ 1 ] * a.first(3) -> Dvector[ 1, 2, 3 ] */ VALUE dvector_first(int argc, VALUE *argv, VALUE ary) {