--- /dev/null
+unit_test_equals("zero order divided_difference_coefficients", ...
+ [1], ...
+ divided_difference_coefficients([0]));
+
+unit_test_equals("first order divided_difference_coefficients", ...
+ [-1, 1] / pi, ...
+ divided_difference_coefficients([0, pi]));
+
+unit_test_equals("second order divided_difference_coefficients", ...
+ [1, -2, 1] / (2*pi^2), ...
+ divided_difference_coefficients([0, pi, 2*pi]));