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() {  }  /*   * 實(shí)例化后，計(jì)算前，先要輸入?yún)?shù)并生成公式 arrayX為采樣點(diǎn)的x軸坐標(biāo)，按照采樣順序排列   * arrayY為采樣點(diǎn)的y軸坐標(biāo)，按照采樣順序與x一一對應(yīng)排列 order   * 為進(jìn)行擬合的階數(shù)。用低階來擬合高階曲線時(shí)可能會不準(zhǔn)確，但階數(shù)過高會導(dǎo)致計(jì)算緩慢   */  public boolean generateFormula(double[] arrayX, double[] arrayY, int order) {    if (arrayX.length != arrayY.length)      return false;    this.order = order;    int len = arrayX.length;    // 擬合運(yùn)算中的x矩陣和y矩陣    matrixA = new double[order + 1][order + 1];    arrayB = new double[order + 1];    // 生成y矩陣以及x矩陣中冪<=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矩陣中冪>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;      }    }    // 實(shí)例化PolynomiaSoluter并解方程組，得到各階的系數(shù)序列factors    PolynomialSoluter soluter = new PolynomialSoluter();    factors = soluter.getResult(matrixA, arrayB);    if (factors == null)      return false;    else      return true;  }  // 根據(jù)輸入坐標(biāo)，以及系數(shù)序列factors計(jì)算指定坐標(biāo)的結(jié)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;  }}