matlab 曲线拟合

[WANGDONG2018]

下面是matlab曲线拟合的结果，其中参数 b2 = 7.642 (7.444, 7.839) ，括号后面两个数的含义是什么？


General model Gauss2:
f(x) = a1*exp(-((x-b1)/c1)^2) + a2*exp(-((x-b2)/c2)^2)


Coefficients (with 95% confidence bounds):
a1 = 0.4719 (-3.714e+004, 3.714e+004)
b1 = 1872 (-5.128e+009, 5.128e+009)
c1 = 1.102e+004 (-1.516e+010, 1.516e+010)
a2 = 1.387 (1.119, 1.655)
b2 = 7.642 (7.444, 7.839)
c2 = 1.757 (1.353, 2.16)

[worldy]

x自变量 b1\c2\b2\c2为常数 f（x）函数值

[worldy]

b2 = 7.642 (7.444, 7.839) 7.642为7.444和7.839的中间值