VB化工参数拟合..pptVIP

2.5 单变量 二次拟合求解公式 由多元函数的极值原理，Q( a0 ,a1 ,a2 )的极小值满足： 整理得多变量一次多项式函数拟合的法方程： （1-18） 2.6 单变量 二次拟合核心代码 对于式（1-14）的方程组，采用简单的克雷默求解方法，为了增加开发程序是灵活性，将2次项处理成X2,这样系数计算公司变成了式（1-18），开发的子程序代码如下： * 华南理工学化学与化工学院方利国开发 * * 华南理工学化学与化工学院方利国开发 * Public Sub Twonihe(x1(), x2(), y(), a0, a1, a2, m) Dim a(4, 4), b(4, 4), s, s1, s2, s3, y1(4) Dim i, j As Integer （求解法方程系数） a(1, 1) = m a(1, 2) = 0 For i = 1 To m a(1, 2) = a(1, 2) + x1(i) Next i a(2, 1) = a(1, 2) a(1, 3) = 0 For i = 1 To m a(1, 3) = a(1, 3) + x2(i) Next I a(3, 1) = a(1, 3) a(2, 2) = 0 For i = 1 To m a(2, 2) = a(2, 2) + x1(i) * x1(i) Next i a(3, 3) = 0 For i = 1 To m a(3, 3) = a(3, 3) + x2(i) * x2(i) Next i a(2, 3) = 0 For i = 1 To m a(2, 3) = a(2, 3) + x1(i) * x2(i) Next i a(3, 2) = a(2, 3) y1(1) = 0 For i = 1 To m y1(1) = y1(1) + y(i) Next i y1(2) = 0 For i = 1 To m y1(2) = y1(2) + x1(i) * y(i) Next i y1(3) = 0 For i = 1 To m y1(3) = y1(3) + x2(i) * y(i) Next i * 华南理工学化学与化工学院方利国开发 * （利用克拉默法则解法方程） s = a(1, 1) * a(2, 2) * a(3, 3) + a(1, 2) * a(2, 3) * a(3, 1) + a(1, 3) * a(2, 1) * a(3, 2) s = s - a(1, 1) * a(2, 3) * a(3, 2) - a(1, 2) * a(2, 1) * a(3, 3) - a(1, 3) * a(2, 2) * a(3, 1) For j = 1 To 3 b(j, 1) = a(j, 1) 交换列后计算行列式的值 a(j, 1) = y1(j) Next j s1 = a(1, 1) * a(2, 2) * a(3, 3) + a(1, 2) * a(2, 3) * a(3, 1) + a(1, 3) * a(2, 1) * a(3, 2) s1 = s1 - a(1, 1) * a(2, 3) * a(3, 2) - a(1, 2) * a(2, 1) * a(3, 3) - a(1, 3) * a(2, 2) * a(3, 1) For j = 1 To 3 a(j, 1) = b(j, 1) Next j For j = 1 To 3 b(j, 2) = a(j, 2) a(j, 2) = y1(j) Next j s2 = a(1, 1) * a(2, 2) * a(3, 3) + a(1, 2) * a(2, 3) * a(3, 1) + a(1, 3) * a(2, 1) * a(3, 2) s2 = s2 - a(1, 1) * a(2, 3) * a(3, 2) - a(1, 2) * a(2, 1) * a(3, 3) - a(1, 3) * a(2, 2) * a(3, 1) For j = 1 To 3 a(j, 2) = b(j, 2) Next j For j = 1 To 3 b(j, 3) = a(j, 3) a(j, 3) = y1(j) Next j s3 = a(1, 1) * a(2, 2) * a(3, 3) + a(1, 2) * a(2, 3) * a(3, 1) + a(1, 3) * a(2, 1) * a(3, 2) s3 = s3 - a(1, 1) * a(2, 3) * a(3, 2)