[Java] apache commons mathで行列演算(ベクトル編)

行列編はこちら→https://qiita.com/AlliumAllium/items/b05bd5195f1b68041ab9

コード

import org.apache.commons.math4.legacy.linear.RealVector;
import org.apache.commons.math4.legacy.linear.MatrixUtils;

public class Test {
    public static void main(String[] args) {
        // 宣言
        RealVector vector1 = MatrixUtils.createRealVector(
                new double[] { 1, 0, -2 });
        System.out.println("v1 =");
        System.out.println(vector1);
        RealVector vector2 = MatrixUtils.createRealVector(
                new double[] { 1, 1, 1 });
        System.out.println("v2 =");
        System.out.println(vector2);
        double s = 3;
        System.out.println("s =");
        System.out.println(s);

        // 次元
        System.out.println("次元 =");
        System.out.println(vector1.getDimension());

        // ノルム(大きさ)
        System.out.println("ノルム||v1|| =");
        System.out.println(vector1.getNorm());

        // L1ノルム
        System.out.println("L1ノルム||v1||_1 =");
        System.out.println(vector1.getL1Norm());

        // 正規化
        System.out.println("正規化 v1/||v1||_1 =");
        System.out.println(vector1.unitVector());

        // 和
        System.out.println("和 v1+v2 =");
        System.out.println(vector1.add(vector2));

        // 差
        System.out.println("差 v1-v2 =");
        System.out.println(vector1.subtract(vector2));

        // 要素の積
        System.out.println("要素の積 {v1_i * v2_i}_i =");
        System.out.println(vector1.ebeMultiply(vector2));

        // 内積
        System.out.println("v1・v2 =");
        System.out.println(vector1.dotProduct(vector2));

        // 外積
        System.out.println("v1 × v2 =");
        System.out.println(vector1.outerProduct(vector2));

        // スカラー倍
        System.out.println("v1*s =");
        System.out.println(vector1.mapMultiply(s));

        // 距離
        System.out.println("d(v1, v2) = ");
        System.out.println(vector1.getDistance(vector2));

        // v1をv2へ射影
        System.out.println("v2への射影ベクトル = ");
        System.out.println(vector1.projection(vector2));

    }
}

結果

v1 =
{1; 0; -2}
v2 =
{1; 1; 1}
s =
3.0
次元 =
3
ノルム||v1|| =
2.23606797749979
L1ノルム||v1||_1 =
3.0
正規化 v1/||v1||_1 =
{0.4472135955; 0; -0.894427191}
和 v1+v2 =
{2; 1; -1}
差 v1-v2 =
{0; -1; -3}
要素の積 {v1_i * v2_i}_i =
{1; 0; -2}
v1・v2 =
-1.0
v1 × v2 =
Array2DRowRealMatrix{{1.0,1.0,1.0},{0.0,0.0,0.0},{-2.0,-2.0,-2.0}}
v1*s =
{3; 0; -6}
d(v1, v2) =
3.1622776601683795
v2への射影ベクトル =
{-0.3333333333; -0.3333333333; -0.3333333333}