def is_atom_convex(self) -> bool:
"""Is the atom convex?
"""
if u.scopes.dpp_scope_active():
# kron is not DPP if any parameters are present.
x = self.args[0]
y = self.args[1]
return ((x.is_constant() or y.is_constant())
and (is_param_free(x) and is_param_free(y)))
else:
return self.args[0].is_constant() or self.args[1].is_constant()
def is_atom_convex(self):
"""Multiplication is convex (affine) in its arguments only if one of
the arguments is constant.
"""
if u.scopes.dpp_scope_active():
# This branch applies curvature rules for DPP.
#
# Because a DPP scope is active, parameters will be
# treated as affine (like variables, not constants) by curvature
# analysis methods.
#
# Like under DCP, a product x * y is convex if x or y is constant.
# If neither x nor y is constant, then the product is DPP
# if one of the expressions is affine in its parameters and the
# other is parameter-free.
x = self.args[0]
y = self.args[1]
return ((x.is_constant() or y.is_constant())
or (is_param_affine(x) and is_param_free(y))
or (is_param_affine(y) and is_param_free(x)))
else:
return self.args[0].is_constant() or self.args[1].is_constant()