$\nabla f$

A = (0.7900836595307545, -0.11901884148648634, 0)
a(x, y) = If[x < 0 ∨ x > 1.5 ∨ y > -0.5 ∨ y < -1, (ℯ^(((-((x + 1)^(2) + (y + 0.5)^(2)))) / 0.5) * 2) + ℯ^(((-((x - 0.5)^(2) + y^(2)))) / 0.5)]
B: (x(A), y(A), a(x(A), y(A)))
b = Derivative(a(x, y), x)
c = Derivative(a(x, y), y)
u = Vector((x(B), y(B), 0), (x(B) + b(x(B), y(B)), y(B) + c(x(B), y(B)), 0))
v = Vector((x(B), y(B), z(B)), (x(B) + b(x(B), y(B)), y(B) + c(x(B), y(B)), z(B)))
l: (b(x(B), y(B))^(2) + c(x(B), y(B))^(2))^(1 / 2)
w = Vector((x(B), y(B), z(B)), (x(B) + b(x(B), y(B)) / l, y(B) + c(x(B), y(B)) / l, z(B) + (b(x(B), y(B))^(2) + c(x(B), y(B))^(2)) / l))