Visual Basic выдает ошибку run-time error 11 division bu zero - VB

Public Sub Задача_3()
Dim A As Single, B As Single, M As Integer, H As Single, X As Single, F As Single, S As String
A = InputBox("Ведите начало отрезка a", "Задача 3 Иринка")
B = InputBox("Введите конец отрезка b", "Задача 3 Иринка")
M = InputBox("Введите число точек m", "Задача 3 Иринка")
H = (B - A) / M
Worksheets(1).Cells(1, 1).Value = "X"
Worksheets(1).Cells(1, 2).Value = "F"
i = 2
For X = A To B Step H
F = (Pi / 2) - (Atn(X / (Sqr(1 - (X ^ 2)))))
X = Format(X, "00.000")
F = Format(F, "00.000")
Worksheets(1).Cells(i, 1).Value = X
Worksheets(1).Cells(i, 2).Value = F
i = i + 1
Next X
i = i + 1
Worksheets(1).Cells(i, 1).Value = "Программу выполнила Иринка"
S = Now
i = i + 1
Worksheets(1).Cells(i, 1).Value = S
End Sub
 
При a = 0.5
b=1
m = 5