Trying to store array values into cells in an excel sheet - arrays

Question

I've been having some problems with storing some calculated values into an excel sheet in specific cells. The complete code is lengthy but I've posted it below. While running with the debugger what I've found is that it is failing when it tries to store this first value in the first step of the following for loop:
For i = 1 To 100
Cells(i, 1).Value = Cmatrix(i, 1)
Cells(i, 2).Value = Cmatrix(i, 2)
Next i
I've also tried it with ActiveSheet.Cells(i, 1).Value but I still just get a #VALUE! error during the first line of the for loop. I've also tried with and without the .Value
The Cmatrix is declared as a variant but I've also declared it as a double before just to see. It is an array from 1-100 and 1-2. I've even tried just setting it equal to 1 but the same problem arrises.
The overall code is rather lengthy but is here with the problem area being closer to the bottom:
Option Explicit
Public Function Test(check As Integer) As Integer
Dim Response As Integer
If check = 1 Then
Response = MsgBox("Boundary Condition 1 selected, is this correct (select No for boundary condition 2)?", vbYesNo, "Boundary Conditions")
If Response = 6 Then
Test = 1
Else
Test = 2
End If
ElseIf check = 2 Then
Response = MsgBox("Boundary Condition 2 selected, is this correct (select No for boundary condition 1)?", vbYesNo, "Boundary Conditions")
If Response = 6 Then
Test = 2
Else
Test = 1
End If
Else
Response = MsgBox("Incorrect Boundary Condition, select Yes for condition 1 and No for condition 2", vbYesNo, "Boundary Conditions")
If Response = 6 Then
Test = 1
Else
Test = 2
End If
End If
End Function
Public Sub Check2(x)
MsgBox ("Value given is outside data range, answer may not be correct, extrapolating from calculated polynomial")
End Sub
Public Function cubic(ByVal r As Range, x As Double, Optional check As Integer = 1) As Double
Dim data() As Double
Dim check1 As Integer
Dim Smatrix() As Double
Dim Tmatrix() As Double
Dim Xmatrix() As Double
Dim Amatrix() As Double
Dim Hmatrix() As Double
Dim Cmatrix(1 To 100, 1 To 2) As Variant
Dim m As Integer
Dim i As Integer, j As Integer
Dim step As Double
Dim chart As Range, c As Range
m = r.Rows.Count
ReDim data(1 To m, 2)
ReDim Smatrix(1 To m, 1 To m)
ReDim Tmatrix(1 To m, 4)
ReDim Xmatrix(1 To m)
ReDim Amatrix(1 To m - 1, 1 To 4)
ReDim Hmatrix(1 To m)
check1 = Test(check)
For i = 1 To m
data(i, 1) = r(i, 1).Value
data(i, 2) = r(i, 2).Value
Next i
Smatrix(1, 1) = 1
Smatrix(m, m) = 1
For i = 1 To m - 1
Hmatrix(i) = data(i + 1, 1) - data(i, 1)
Next i
If check1 = 2 Then
Smatrix(1, 2) = -1
Smatrix(m, m - 1) = -1
End If
For i = 2 To m - 1
Smatrix(i, i - 1) = Hmatrix(i - 1)
Smatrix(i, i + 1) = Hmatrix(i)
Smatrix(i, i) = 2 * (Hmatrix(i - 1) + Hmatrix(i))
Next i
For i = 2 To m - 1
Tmatrix(i, 4) = 6 * ((data(i + 1, 2) - data(i, 2)) / Hmatrix(i) - (data(i, 2) - data(i - 1, 2)) / Hmatrix(i - 1))
Next i
For i = 1 To m
If i <> 1 Then
Tmatrix(i, 1) = Smatrix(i, i - 1)
End If
Tmatrix(i, 2) = Smatrix(i, i)
If i <> m Then
Tmatrix(i, 3) = Smatrix(i, i + 1)
End If
Next i
For i = 2 To m
Tmatrix(i, 1) = Tmatrix(i, 1) / Tmatrix(i - 1, 2)
Tmatrix(i, 2) = Tmatrix(i, 2) - Tmatrix(i, 1) * Tmatrix(i - 1, 3)
Tmatrix(i, 4) = Tmatrix(i, 4) - Tmatrix(i, 1) * Tmatrix(i - 1, 4)
Next i
Xmatrix(m) = Tmatrix(m, 4) / Tmatrix(m, 2)
For i = m - 1 To 1 Step -1
Xmatrix(i) = (Tmatrix(i, 4) - Tmatrix(i, 3) * Xmatrix(i + 1)) / Tmatrix(i, 2)
Next i
For i = 1 To m - 1
Amatrix(i, 1) = (Xmatrix(i + 1) - Xmatrix(i)) / 6 * Hmatrix(i)
Amatrix(i, 2) = Xmatrix(i) / 2
Amatrix(i, 3) = (data(i + 1, 2) - data(i, 2)) / Hmatrix(i) - Hmatrix(i) * Xmatrix(i) / 2 - Hmatrix(i) * (Xmatrix(i + 1) - Xmatrix(i)) / 6
Amatrix(i, 4) = data(i, 2)
Next i
step = (data(m, 1) - data(1, 1)) / 100
For i = 0 To (m - 1)
Cmatrix(i + 1, 1) = data(1, 1) + i * step
Next i
For j = 1 To m
If Cmatrix(j, 1) = data(m, 1) Then
Cmatrix(j, 2) = data(m, 2)
Else
For i = 1 To m - 1
If data(i, 1) < Cmatrix(j, 1) And Cmatrix(j, 1) < data(i + 1, 1) Then
Cmatrix(j, 2) = Amatrix(i, 1) * (Cmatrix(j, 1) - data(i, 1)) ^ 3 + Amatrix(i, 2) * (Cmatrix(j, 1) - data(i, 1)) ^ 2 + Amatrix(i, 3) * (Cmatrix(j, 1) - data(i, 1)) + Amatrix(i, 4)
ElseIf Cmatrix(j, 1) = data(i, 1) Then
Cmatrix(j, 2) = data(i, 2)
End If
Next i
End If
Next j
If x < data(1, 1) Or x > data(m, 1) Then
Call Check2(x)
If x < data(1, 1) Then
cubic = Amatrix(1, 1) * (x - data(1, 1)) ^ 3 + Amatrix(1, 2) * (x - data(1, 1)) ^ 2 + Amatrix(1, 3) * (x - data(1, 1)) + Amatrix(1, 4)
ElseIf x > data(m, 1) Then
cubic = Amatrix(m - 1, 1) * (x - data(m - 1, 1)) ^ 3 + Amatrix(m - 1, 2) * (x - data(m - 1, 1)) ^ 2 + Amatrix(m - 1, 3) * (x - data(m - 1, 1)) + Amatrix(m - 1, 4)
End If
ElseIf x = data(m, 1) Then
cubic = data(m, 2)
Else
For i = 1 To m - 1
If data(i, 1) < x And x < data(i + 1, 1) Then
cubic = Amatrix(i, 1) * (x - data(i, 1)) ^ 3 + Amatrix(i, 2) * (x - data(i, 1)) ^ 2 + Amatrix(i, 3) * (x - data(i, 1)) + Amatrix(i, 4)
ElseIf x = data(i, 1) Then
cubic = data(i, 2)
End If
Next i
End If
For i = 1 To 100
Cells(i, 1).Value = Cmatrix(i, 1)
Cells(i, 2).Value = Cmatrix(i, 2)
Next i
Set chart = Range("A1:B100")
Dim cht As Object
Set cht = ActiveSheet.Shapes.AddChart2(XlChartType:=xlXYScatterSmooth)
cht.chart.SetSourceData Source:=chart
End Function