/*
 *  call-seq:
 *     dvector.trim!(cutoff=1e-6)   ->  dvector
 *  
 *  Each entry x in _dvector_ having absolute value less than _cutoff_ is replaced by 0.
 *     
 *     a = Dvector[ 1.1, 1e-20, -5.3 ]
 *     a.trim!  -> Dvector[ 1.1, 0, -5.3 ]
 */ 
VALUE dvector_trim_bang(int argc, VALUE *argv, VALUE self) {