For models in the form of noninvertible maps we propose a numerical method
to calculate a class of basin bifurcation sets in a parameter space. It is
known that basin bifurcations may result from the contact of a basin bounda
ry with the critical curve (locus of points having two coincident rank-one
preimages) segment. Therefore, when the map is smooth, we propose the metho
d to obtain the tangent points of a basin boundary (stable set of saddle ty
pe periodic points) and a critical curve. Numerical examples for a two-dime
nsional quadratic noninvertible map are illustrated and new results of basi
n bifurcations are shown.