我正在使用E.J.的SolvStat宏。 Billo是《 Excel for Chemists》一书的作者,我无法弄清楚如何将偏导数计算为除0以外的任何值,因为我看不到任何明确的赋值会改变任一YCalc()数组的值值或calc_ys范围值。以下代码摘自该宏:
Dim YObsd(), YCalc(), ParmValu(), PartialDeriv(), Product(), ProdArray()
Set calc_ys = Application.InputBox("Podaj zakres wartości Y obliczonych z modelu." & msg1, _
"SOLVER STATISTICS - Krok 2 z 4", , , , , , 8)
ReDim YObsd(N), YCalc(N)
x = 1
For Each F In calc_ys
YCalc(x) = F.Value
x = x + 1
Next
Set Parms = Application.InputBox("Zaznacz komórki zawierające współczynniki obliczone metodą najmniejszych kwadratów przez Solvera." & msg2, _
"SOLVER STATISTICS – Krok 3 z 4", , , , , , 8)
N3 = Parms.Count
x = 1
For Each cell In Parms
ParmValu(x) = cell.Value
x = x + 1
Next
RMSD = Sqr(SSresiduals / (N - N3))
'Calculate table of partial differentials
increment = 0.000001
'1E-6 seems to be optimum value for increment for numerical differentiation.
'1E-3 is too large, 1E-12 is too small. 1E-9 gives results almost identical to 1E-6.
y = 1
For Each parm In Parms
parm.Value = parm * (1 + increment) 'Increase regression coeffs by a small increment.
If parm = 0 Then parm.Value = 1E-100 'If cell contains zero exactly, replace it with very small value
CheckErrorSum = 0
x = 1
For Each cell In calc_ys
PartialDeriv(x, y) = (cell - YCalc(x)) / (parm * increment) 'Partial deriv = delta(function)/delta(parameter)
CheckErrorSum = CheckErrorSum + PartialDeriv(x, y) 'This sum used only for error checking.
x = x + 1
Next cell
parm.Value = ParmValu(y) 'Restore original parameter value
If CheckErrorSum = 0 Then
MsgBox "Błąd w obliczeniach macierzy." & Chr(13) & Chr(13) &
"Najpowszechniejsze błędy: " & Chr(13) & Chr(13) & _
"1. Niepoprawny wybór komórek Y(obl)." & Chr(13) & Chr(13) & _
"2. Niepoprawny wybór komórek zawierających współczynniki regresji
" & Chr(13) & Chr(13) & "Zatrzymanie programu.", 16, "UNKNOWN ERROR"
Exit Sub
End If
y = y + 1
Next parm
YCalc(x)值包含从Excel中的“范围”分配的值;但是,单元格(calc_ys中的元素)是一个略微的值,但是从代码来看,似乎没有任何区别。为了计算偏导数,应该有所不同,但是我不明白该代码为何/为什么为这两个变量产生不同的值。
以下是完整代码的链接:http://ue.poznan.pl/data/upload/articles/20140213/330de4761384630218/solvstat.doc
答案 0 :(得分:0)
由于calc_ys是一个单元格范围,因此它不包含电子表格中的显示值,而是包含用于计算显示值的公式。这些公式引用了参数,这些参数已在偏导数部分中进行了修改;因此,Range中的calc_ys单元也被修改。