/*
 *  call-seq:
 *     dtable.safe_inv!(cutoff)   ->  dtable
 *  
 *  Replaces each entry x in _dtable_ by sign(x)/_cutoff_ if abs(x) < _cutoff_, 1/x otherwise.
 *     
 */ VALUE dtable_safe_inv_bang(int argc, VALUE *argv, VALUE self) {