  The spontaneous scalarization of Schwarzscild-AdS is investigated in the
Einstein-scalar-Gauss--Bonnet (ESGB) theory. Firstly, we construct scalarized
AdS black holes numerically. Secondly, making use of the homotopy analysis
method (HAM), we obtain analytical approximate solutions for scalarized AdS
black holes in the ESGB theory. It is found that scalarized AdS black holes
constructed numerically are consistent with analytical approximate solutions in
the whole space.
