## Test the optimal points.

unit_test_equals("himmelblau(3,2) == 0", ...
		 0, ...
		 himmelblau(3,2));

x1 = -2.805118086952745;
x2 = 3.131312518250573;
msg = sprintf("himmelblau(%f, %f) == 0", x1, x2);
unit_test_equals(msg, ...
		 true, ...
		 norm(himmelblau(x1, x2)) < 1e-12);

x1 = -3.779310253377747;
x2 = -3.283185991286170;
msg = sprintf("himmelblau(%f, %f) == 0", x1, x2);
unit_test_equals(msg, ...
		 true, ...
		 norm(himmelblau(x1, x2)) < 1e-12);

x1 = 3.584428340330492;
x2 = -1.848126526964404;
msg = sprintf("himmelblau(%f, %f) == 0", x1, x2);
unit_test_equals(msg, ...
		 true, ...
		 norm(himmelblau(x1, x2)) < 1e-12);
