rowvector.java

来自「一个一元曲线多项式数值演示例子」· Java 代码 · 共 149 行

package numbercruncher.matrix;

public class RowVector
    extends Matrix {
  //--------------//
  // Constructors //
  //--------------//

  /**
   * Constructor.
   * @param n the number of elements
   */
  public RowVector(int n) {
    super(1, n);
  }

  /**
   * Constructor.
   * @param values the array of values
   */
  public RowVector(float values[]) {
    set(values);
  }

  /**
   * Constructor.
   * @param m the matrix (only the first row used)
   */
  private RowVector(Matrix m) {
    set(m);
  }

  //---------//
  // Getters //
  //---------//

  /**
   * Return the row vector's size.
   */
  public int size() {
    return nCols;
  }

  /**
   * Copy the values of this matrix.
   * @return the copied values
   */
  public float[] copyValues1D() {
    float v[] = new float[nCols];

    for (int c = 0; c < nCols; ++c) {
      v[c] = values[0][c];
    }

    return v;
  }

  /**
   * Return the i'th value of the vector.
   * @param i the index
   * @return the value
   */
  public float at(int i) {
    return values[0][i];
  }

  //---------//
  // Setters //
  //---------//

  /**
   * Set this row vector from a matrix. Only the first row is used.
   * @param m the matrix
   */
  private void set(Matrix m) {
    this.nRows = 1;
    this.nCols = m.nCols;
    this.values = m.values;
  }

  /**
   * Set this row vector from an array of values.
   * @param values the array of values
   */
  protected void set(float values[]) {
    this.nRows = 1;
    this.nCols = values.length;
    this.values = new float[1][];

    this.values[0] = values;
  }

  /**
   * Set the i'th value of the vector.
   * @param i the index
   * @param value the value
   */
  public void set(int i, float value) {
    values[0][i] = value;
  }

  //-------------------//
  // Vector operations //
  //-------------------//

  /**
   * Add another row vector to this row vector.
   * @param rv the other row vector
   * @return the sum row vector
   * @throws numbercruncher.MatrixException for invalid size
   */
  public RowVector add(RowVector rv) throws MatrixException {
    return new RowVector(super.add(rv));
  }

  /**
   * Subtract another row vector from this row vector.
   * @param rv the other row vector
   * @return the sum row vector
   * @throws numbercruncher.MatrixException for invalid size
   */
  public RowVector subtract(RowVector rv) throws MatrixException {
    return new RowVector(super.subtract(rv));
  }

  /**
   * Compute the Euclidean norm.
   * @return the norm
   */
  public float norm() {
    double t = 0;
    for (int c = 0; c < nCols; ++c) {
      float v = values[0][c];
      t += v * v;
    }

    return (float) Math.sqrt(t);
  }

  /**
   * Print the vector values.
   */
  public void print() {
    for (int c = 0; c < nCols; ++c) {
      System.out.print("  " + values[0][c]);
    }
    System.out.println();
  }
}