#include once "big_int/big_integer.bi"

Function DominoTilingCount(m As Integer, n As Integer) As Bigint
    Dim As Double prod = 1.0
    Dim As Integer jmax = m \ 2, kmax = n \ 2

    For j As Integer = 1 To jmax
        For k As Integer = 1 To kmax
            Dim cj As Double = Cos(j * 4 * Atn(1) / (m + 1))
            Dim ck As Double = Cos(k * 4 * Atn(1) / (n + 1))
            Dim term As Double = 4 * cj * cj + 4 * ck * ck
            prod *= term
        Next
    Next

    ' Round only at the end and convert to Bigint
    Return Bigint(Clng(prod + 0.5))
End Function

Function FactBig(n As Integer) As Bigint
    Dim As Bigint res = 1
    For i As Integer = 2 To n
        res *= i
    Next
    Return res
End Function

' Main program
Dim As Double t4 = Timer

Dim As BigInt arrang = DominoTilingCount(7, 8)
Dim As BigInt perms = FactBig(28)
Dim As BigInt flips = 2^28

Print "Arrangements ignoring values: "; arrang
Print "Permutations of 28 dominos: "; perms
Print "Permuted arrangements ignoring flipping dominos: "; arrang * perms
Print "Possible flip configurations: "; flips
Print "Possible permuted arrangements with flips: "; flips * arrang * perms

Dim As Double t5 = Timer
Print Using !"\nTook #.##### seconds."; t5-t4

Sleep