Function GAMDEV(IA, IDUM&)
    If IA < 1 Then Print "Abnormal exit": Exit Function
    If IA < 6 Then
        X = 1#
        For J = 1 To IA
            X = X * RAN1(IDUM&)
        Next J
        X = -Log(X)
    Else
      Do
        Do
          Do
            V1 = 2# * RAN1(IDUM&) - 1#
            V2 = 2# * RAN1(IDUM&) - 1#
          Loop While V1 ^ 2 + V2 ^ 2 > 1#
          Y = V2 / V1
          AM = IA - 1
          S = Sqr(2# * AM + 1#)
          X = S * Y + AM
        Loop While X <= 0!
        E = (1# + Y ^ 2) * Exp(AM * Log(X / AM) - S * Y)
      Loop While RAN1(IDUM&) > E
    End If
    GAMDEV = X
End Function