Error 9: Subscript out of range

Option Explicit
 
Sub R_K()
Dim T0, T1, T As Single
Dim K1, K2, K3, K4, Q1, Q2, Q3, Q4 As Single
 
Dim H As Single
Dim Y0() As Single
Dim Y1() As Single
Dim N As Integer
Dim I As Integer
Dim J As Integer
T0 = 0: T1 = 100: N = 15
H = (T1 - T0) / N
Y0(0) = 340
Y1(0) = 35
T = T0
For I = 0 To N
For J = 0 To N
T = T + H
K1 = F1(T, Y0(I), Y1(I))
Q1 = F2(T, Y0(J), Y1(J))
K2 = F1(T + H / 3, Y0(I) + (H / 3) * K1, Y1(I) + H * Q1 / 3)
Q2 = F2(T + H / 3, Y0(J) + (H / 3) * K1, Y1(J) + H * Q1 / 3)
K3 = F1(T + 2 * H / 3, Y0(I) - (H * K1 / 3) + H * K2, Y1(I) - (H * Q1 / 3) + H * Q2)
Q3 = F2(T + 2 * H / 3, Y0(J) - (H * K1 / 3) + H * K2, Y1(J) - (H * Q1 / 3) + H * Q2)
K4 = F1(T + H, Y0(I) + H * K1 - H * K2 + H * K3, Y1(I) + H * K1 - H * K2 + H * K3)
Q4 = F2(T + H, Y0(J) + H * K1 - H * K2 + H * K3, Y1(J) + H * K1 - H * K2 + H * K3)
Y0(I + 1) = Y0(I) + (K1 + 3 * K2 + 3 * K3 + K4) * H / 8
Y1(J + 1) = Y1(J) + (Q1 + 3 * Q2 + 3 * Q3 + Q4) * H / 8
Next J
Next I
 
 
For I = 0 To N
For J = 0 To N
Worksheets("Output").Cells(I + 1).Value = Y0(I)
Worksheets("Output").Cells(I + 2).Value = Y1(J)
Next J
Next I
 
End Sub
 
Function F1(T As Single, Y0 As Single, Y1 As Single) As Single
Dim A As Single
Dim B As Single
Dim C As Single
A = 0.05: B = 0.00005: C = 0.002
F1 = Y0(A - B * Y0) - C * Y1
End Function
Function F2(T As Single, Y0 As Single, Y1 As Single) As Single
Dim D As Single
Dim E As Single
E = 0.002: D = 0.03
F2 = Y1(E * Y0 - D)
End Function

'.....................
'.....................
Dim H As Single
Dim Y0() As Single
Dim Y1() As Single
Dim N As Integer
Dim I As Integer
Dim J As Integer
T0 = 0: T1 = 100: N = 15
ReDim Y0(N),Y1(N) 
H = (T1 - T0) / N
Y0(0) = 340
Y1(0) = 35
T = T0
For I = 0 To N-1
For J = 0 To N-1
'.....................
'.....................

Function F2(T As Single, Y0 As Single, Y1 As Single) As Single
Dim D As Single
Dim E As Single
E = 0.002: D = 0.03
F2 = Y1(E * Y0 - D) ' Y1  вроде бы элемент массива с загадочным индексом, Y0 тоже непонятно что.
End Function