/*
 *  call-seq:
 *     dvector.safe_inv!(cutoff=1e-99)   ->  dvector
 *  
 *  Replaces each entry x in _dvector_ by sign(x)/_cutoff_ if abs(x) < _cutoff_, 1/x otherwise.
 *     
 */ 
VALUE dvector_safe_inv_bang(int argc, VALUE *argv, VALUE self) {