[GitHub] [flink] c4emmmm commented on a change in pull request #8631: [FLINK-12745][ml] add sparse and dense vector class, and dense matrix class with basic operations.

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c4emmmm commented on a change in pull request #8631: [FLINK-12745][ml] add sparse and dense vector class, and dense matrix class with basic operations.
URL: https://github.com/apache/flink/pull/8631#discussion_r294215696
 
 

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 File path: flink-ml-parent/flink-ml-lib/src/main/java/org/apache/flink/ml/common/matrix/DenseMatrix.java
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 @@ -0,0 +1,751 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+package org.apache.flink.ml.common.matrix;
+
+import java.io.Serializable;
+import java.util.Arrays;
+
+/**
+ * Dense Matrix.
+ */
+public class DenseMatrix implements Serializable {
+	/* ------------------------
+	Class variables
+     * ------------------------ */
+
+	/**
+	 * Row and column dimensions.
+	 */
+	int m, n;
+
+	/**
+	 * Array for internal storage of elements.
+	 * <p>
+	 * The matrix data is stored in column major format internally.
+	 */
+	double[] data;
+
+    /* ---------------------------------------------------
+	 * Constructors
+     * --------------------------------------------------- */
+
+	/**
+	 * Construct an empty matrix.
+	 */
+	public DenseMatrix() {
 
 Review comment:
   I suppose all matrixes should be declared with its dimension, so the empty constructor should be removed and the variables m, n, data should be declared final. Please let me know if there's any scenario that the matrix can be undefined dimension.

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