Option Explicit
Public Deriv_Approx As Boolean
Sub Funct(f, c, x)
Dim n&, i&
n = UBound(x)
ReDim f(1 To n)
For i = 1 To n
f(i) = Exp(c(1) * x(i)) + c(2)
Next i
End Sub
Sub DFunct(df, c, x)
Dim m&, n&, i&, j&, t#, df0(), tol#
m = UBound(c)
n = UBound(x)
ReDim df(1 To n, 1 To m)
If Deriv_Approx Then
DFunctApprox df, c, x
Else
For i = 1 To n
df(i, 1) = x(i) * Exp(c(1) * x(i))
df(i, 2) = 1
Next i
End If
End Sub
Private Sub DFunctApprox(df, c, x)
Dim h#, m&, n&, j&, i&, t(), f0(), f1()
h = 10 ^ -4
m = UBound(c)
ReDim t(1 To m)
For j = 1 To m
For i = 1 To m
If i = j Then
t(i) = c(i) + h / 2
Else
t(i) = c(i)
End If
Next i
Funct f1, t, x
For i = 1 To m
If i = j Then
t(i) = c(i) - h / 2
Else
t(i) = c(i)
End If
Next i
Funct f0, t, x
n = UBound(f1)
If j = 1 Then ReDim df(1 To n, 1 To m)
For i = 1 To n
df(i, j) = (f1(i) - f0(i)) / h
Next i
Next j
End Sub