//线性拟合（不一定过原点）
//公式：http://i1.piimg.com/588926/c241d90e3eb2cfdb.png
public static LfReValue linearFitFunc(double[] a, double[] b, int n)
{
LfReValue temp = new LfReValue();
double a_sum = 0, b_sum = 0;
double a_avg, b_avg;
double p1 = 0, p2 = 0, p3 = 0, p4 = 0;
double a_temp, b_temp, r_temp;
for (int i = 0; i < n; i++)
{
a_sum += a[i];
b_sum += b[i];
p3 += a[i] * a[i];//p3
}
a_avg = a_sum / n;
b_avg = b_sum / n;
for (int i = 0; i < n; i++)
{
p1 += a[i] * b[i];//p1
}
p2 = n * a_avg * b_avg; //p2
p4 = n * a_avg * a_avg; //p4
b_temp = (p1 - p2) / (p3 - p4); //求出拟合参数b
a_temp = b_avg - b_temp * a_avg; //求出拟合参数a
//下面计算相关系数r
double r_value1 = 0, r_value2 = 0, r_value3 = 0;
for (int i = 0; i < n; i++)
{
r_value1 += (a[i] - a_avg) * (b[i] - b_avg);
r_value2 += (a[i] - a_avg) * (a[i] - a_avg);
r_value3 += (b[i] - b_avg) * (b[i] - b_avg);
}
r_temp = r_value1 / (Math.Sqrt(r_value2) * Math.Sqrt(r_value3));
temp.setA(a_temp);
temp.setB(b_temp);
temp.setR(r_temp);
return(temp);
}
//线性拟合：过原点情况
//公式：http://i4.buimg.com/588926/822a2c20ebbe24a6.png
public static LfReValue linearFitFunc_zero(double[] x, double[] y, int n)
{
LfReValue temp = new LfReValue();
double shan = 0, xia = 0;
for (int i = 0; i < x.Length; i++)
{
shan += x[i] * y[i];
xia += x[i] * x[i];
}
temp.setA(0);
temp.setB(shan / xia);
temp.setR(calc_r_xgxs(x, y));
return(temp);
}
//线性拟合过空白
//公式：http://chuantu.biz/t5/85/1494685716x2890171456.gif
public static LfReValue linearFitFunc_blank(double[] a, double[] b, int n)
{
LfReValue temp = new LfReValue();
double a_sum = 0, b_sum = 0;
double a_avg, b_avg;
double p1 = 0, p2 = 0, p3 = 0, p4 = 0, p5 = 0, p6 = 0, p7 = 0;
double a_temp, b_temp, r_temp;
//空白坐标
double x0 = a[0];
double y0 = b[0];
for (int i = 1; i < n; i++)
{
a_sum += a[i];
b_sum += b[i];
p1 += a[i] * b[i];
p5 += a[i] * a[i];
}
a_avg = a_sum / (n - 1);
b_avg = b_sum / (n - 1);
p2 = (n - 1) * x0 * y0;
p3 = (n - 1) * y0 * a_avg;
p4 = (n - 1) * x0 * b_avg;
p6 = 2 * (n - 1) * x0 * a_avg;
p7 = (n - 1) * x0 * x0;
b_temp = (p1 + p2 - p3 - p4) / (p5 - p6 + p7);
a_temp = y0 - b_temp * x0;
r_temp = calc_r_xgxs(a, b);
temp.setA(a_temp);
temp.setB(b_temp);
temp.setR(r_temp);
return(temp);
}