--- /dev/null
+expected_A = [-1, 0, 0, 0, 0; ...
+ -16, 32, -16, 0, 0; ...
+ 0, -16, 32, -16, 0; ...
+ 0, 0, -16, 32, -16; ...
+ 0, 0, 0, 0, -1];
+
+unit_test_equals("Homework #1 problem #1 Poisson matrix is correct", ...
+ true, ...
+ expected_A == poisson_matrix(4, 0, 1));