/*
 *  call-seq:
 *     dvector.asinh   ->  a_dvector
 *  
 *  Returns of copy of _dvector_ with entry x replaced by asinh(x).
 *     
 *     a = Dvector[ 0.1, -0.2, 0.3 ]
 *     a.asinh   -> Dvector[ asinh(0.1), asinh(-0.2), asinh(0.3) ]
 */ 
VALUE dvector_asinh(VALUE ary) {