Java n阶曲线拟合功能 Java实现的n阶曲线拟合功能示例

package commonAlgorithm;
import commonAlgorithm.PolynomialSoluter;
import java.lang.Math;
public class LeastSquare {
  private double[][] matrixA;
  private double[] arrayB;
  private double[] factors;
  private int order;
  public LeastSquare() {
  }
  /*
   * 实例化后，计算前，先要输入参数并生成公式 arrayX为采样点的x轴坐标，按照采样顺序排列
   * arrayY为采样点的y轴坐标，按照采样顺序与x一一对应排列 order
   * 为进行拟合的阶数。用低阶来拟合高阶曲线时可能会不准确，但阶数过高会导致计算缓慢
   */
  public boolean generateFormula(double[] arrayX, double[] arrayY, int order) {
    if (arrayX.length != arrayY.length)
      return false;
    this.order = order;
    int len = arrayX.length;
    // 拟合运算中的x矩阵和y矩阵
    matrixA = new double[order + 1][order + 1];
    arrayB = new double[order + 1];
    // 生成y矩阵以及x矩阵中幂<=order的部分
    for (int i = 0; i < order + 1; i++) {
      double sumX = 0;
      for (int j = 0; j < len; j++) {
        double tmp = Math.pow(arrayX[j], i);
        sumX += tmp;
        arrayB[i] += tmp * arrayY[j];
      }
      for (int j = 0; j <= i; j++)
        matrixA[j][i - j] = sumX;
    }
    // 生成x矩阵中幂>order的部分
    for (int i = order + 1; i <= order * 2; i++) {
      double sumX = 0;
      for (int j = 0; j < len; j++)
        sumX += Math.pow(arrayX[j], i);
      for (int j = i - order; j < order + 1; j++) {
        matrixA[i - j][j] = sumX;
      }
    }
    // 实例化PolynomiaSoluter并解方程组，得到各阶的系数序列factors
    PolynomialSoluter soluter = new PolynomialSoluter();
    factors = soluter.getResult(matrixA, arrayB);
    if (factors == null)
      return false;
    else
      return true;
  }
  // 根据输入坐标，以及系数序列factors计算指定坐标的结果
  public double calculate(double x) {
    double result = factors[0];
    for (int i = 1; i <= order; i++)
      result += factors[i] * Math.pow(x, i);
    return result;
  }
}