~1.4% of test cases fail

When I run it, I get ~1.4% failing test cases.  Here's an example of one:

        {4.000010, 11.000005}, {4.999991, 4.999999}, {8.999989, 8.999995}
        {3.999999, 10.999990}, {5.000005, 4.999998}, {9.000001, 8.999989}

Here's another:

        {3.999993, 11.000011}, {4.999998, 5.000003}, {8.999994, 9.000011}
        {3.999994, 10.999999}, {5.000001, 4.999989}, {9.000001, 9.000003}