def rs_cosh(p, x, prec):
 if rs_is_puiseux(p, x):
  return rs_puiseux(rs_cosh, p, x, prec)
 t = rs_exp(p, x, prec)
 t1 = rs_series_inversion(t, x, prec)
 return ((t + t1) / 2)

def rs_cosh ( p , x , prec ) : if rs_is_puiseux ( p , x ) : return rs_puiseux ( rs_cosh , p , x , prec ) t = rs_exp ( p , x , prec ) t1 = rs_series_inversion ( t , x , prec ) return ( ( t + t1 ) / 2 )
hyperbolic cosine of a series return the series expansion of the cosh of p .