public class LeastSquares {public static void matching(double[] x, double[] y, double[] input, double fully) {double k = getK(x, y);double b = getB(x, y);System.out.println("线性回归系数 k 值：\t" + k + "\n" + "线性回归系数 b 值：\t" + 
b);double maxy = 0; //用来记录最大偏差//寻找最大偏差for (int i = 0; i < input.length; i++) {if (Math.abs(k * input[i] + b - y[i]) > maxy){maxy = Math.abs(k * input[i] + b - y[i]);}}System.out.println("最大偏差为：" + maxy);//求灵敏度double s = 0;double sum = 0;for (int i = 1; i < y.length; i++) {sum += y[i] - y[i-1];}s = sum / (y.length - 1) / 20;System.out.println("灵敏度为：" + Math.abs(s));//求非线性误差System.out.println("非线性误差为：" + Math.abs(maxy/fully*100) + "%");}//返回 x 的系数 k 公式：k = (n sum( xy ) - sum( x ) sum( y )) / (n sum( x^2 )-sum(x) ^ 2)public static double getK(double[] x, double[] y) {int n = x.length;return (double) ((n * pSum(x, y) - sum(x) * sum(y)) / (n * sqSum(x) - Math.pow(sum(x), 
2)));}//返回常量系数系数 b 公式：b = sum( y ) / n - k * sum( x ) / npublic static double getB(double[] x, double[] y) {int n = x.length;double k = getK(x, y);return sum(y) / n - k * sum(x) / n;}//求和private static double sum(double[] ds) {double s = 0;for (double d : ds){s = s + d;}return s;}//求平方和private static double sqSum(double[] ds) {double s = 0;for (double d : ds) {s = (double) (s + Math.pow(d, 2));}return s;}//返回对应项相乘后的和private static double pSum(double[] x, double[] y) {double s = 0;for (int i = 0; i < x.length; i++) {s = s + x[i] * y[i];}return s;}public static void main(String[] args) {double[] x1 = {52.5,55,60,65,70,75,80,85,90,95,100};double[] y1 = {0,-0.54,-1.46,-2.32,-3.20,-4.06,-4.90,-5.72,-6.51,-7.31,-8.01};double[] inputs1 = x1;System.out.println("Pt100 热电阻测温实验拟合直线：");matching(x1, y1,inputs1,y1[y1.length-1]);}
}