Planning: added a regularization test in spline_2d_kernel.

modules/planning/math/smoothing_spline/BUILD

@@ -308,4 +308,16 @@ cc_test(
     ],
 )
 
+cc_test(
+    name = "spline_2d_kernel_test",
+    size = "small",
+    srcs = [
+        "spline_2d_kernel_test.cc",
+    ],
+    deps = [
+        ":spline_2d_kernel",
+        "@gtest//:main",
+    ],
+)
+
 cpplint()

modules/planning/math/smoothing_spline/spline_2d_kernel_test.cc

+/******************************************************************************
+ * Copyright 2017 The Apollo Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *****************************************************************************/
+
+/**
+ * @file
+ **/
+#include "modules/planning/math/smoothing_spline/spline_2d_kernel.h"
+
+#include "glog/logging.h"
+#include "gtest/gtest.h"
+
+namespace apollo {
+namespace planning {
+
+TEST(Spline2dKernel, add_regularization) {
+  std::vector<double> x_knots = {0.0, 1.0, 2.0, 3.0};
+  int32_t spline_order = 4;
+  Spline2dKernel kernel(x_knots, spline_order);
+
+  kernel.AddRegularization(0.2);
+
+  std::cout << kernel.kernel_matrix() << std::endl;
+
+  for (int i = 0; i < kernel.kernel_matrix().rows(); ++i) {
+    for (int j = 0; j < kernel.kernel_matrix().cols(); ++j) {
+      if (i == j) {
+        EXPECT_DOUBLE_EQ(kernel.kernel_matrix()(i, j), 0.4);
+      } else {
+        EXPECT_DOUBLE_EQ(kernel.kernel_matrix()(i, j), 0.0);
+      }
+    }
+  }
+
+  for (int i = 0; i < kernel.offset().rows(); ++i) {
+    for (int j = 0; j < kernel.offset().cols(); ++j) {
+      EXPECT_DOUBLE_EQ(kernel.offset()(i, j), 0.0);
+    }
+  }
+}
+
+}  // namespace planning
+}  // namespace apollo