/*
 *  call-seq:
 *     dtable.set(float)  -> dtable
 *     dtable.set(a_dtable)  -> dtable
 *  
 *  Modifies the entries of _dtable_ array.  If the argument is a float, then all of the
 *  entries are set to that value.  If the argument is another Dtable array, then it must
 *  be the size as _dtable_, and its contents are copied to _dtable_.
 */ VALUE dtable_set(VALUE ary, VALUE val) {