--- /dev/null
+unit_test_equals("sin[0] == 0", ...
+ 0, ...
+ divided_difference(@sin, 0));
+
+unit_test_equals("sin[0, pi] == 0", ...
+ 0, ...
+ divided_difference(@sin, [0,pi]));
+
+unit_test_equals("sin[0, pi, 2*pi] == 0", ...
+ 0, ...
+ divided_difference(@sin, [0,pi,2*pi]));