public void GBMSquaredLoss_UpdateResiduals()
        {
            var targets     = new double[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            var predictions = new double[] { 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 };
            var actual      = new double[targets.Length];
            var sut         = new GradientBoostSquaredLoss();

            sut.UpdateResiduals(targets, predictions, actual, targets.Select(t => true).ToArray());

            var expected = new double[] { -4, -3, -2, -1, 0, 1, 2, 3, 4 };

            CollectionAssert.AreEqual(expected, actual);
        }
        public void GBMSquaredLoss_UpdateResiduals_Indexed()
        {
            var targets     = new double[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            var predictions = new double[] { 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 };
            var actual      = new double[targets.Length];
            var inSample    = new bool[] { true, false, true, false, true, false, true, false, true };
            var sut         = new GradientBoostSquaredLoss();

            sut.UpdateResiduals(targets, predictions, actual, inSample);

            var expected = new double[] { -4, 0.0, -2, 0.0, 0, 0.0, 2, 0.0, 4 };

            CollectionAssert.AreEqual(expected, actual);
        }