Code:
'+=====================================================================================================================================+
'|                                                                                                                                     |
'|                                    An additional set of mathematical functions for Visual Basic 6                                   |
'|                                                                                                                                     |
'|                                           Кривоус Анатолий Анатольевич (The trick)                                                  |
'|                                                                                                                                     |
'+=====================================================================================================================================+

Private Declare Function GetMem2 Lib "msvbvm60" (pSrc As Any, pDst As Any) As Long
Private Declare Function GetMem4 Lib "msvbvm60" (pSrc As Any, pDst As Any) As Long
Private Declare Function ArrPtr Lib "msvbvm60" Alias "VarPtr" (arr() As Any) As Long

Public Type Complex
    R   As Double
    I   As Double
End Type

Public Type Matrix
    Col As Long                 ' Number of columns
    Row As Long                 ' Number of rows
    D() As Double
End Type

Public Const PI = 3.14159265358979
Public Const E = 2.71828182845905

Private Const PI2 = PI / 2

'+=====================================================================================================================================+
'|                                                            Real numbers                                                             |
'+=====================================================================================================================================+

' // From degree to radians
Public Function Deg(ByVal Value As Double) As Double
    Deg = 1.74532925199433E-02 * Value
End Function

' // The logarithm to the base of a real number X
Public Function LogX(ByVal Value As Double, ByVal Base As Double) As Double
    LogX = Log(Value) / Log(Base)
End Function

' // The decimal logarithm of a real number
Public Function Log10(ByVal Value As Double) As Double
    Log10 = Log(Value) / 2.30258509299405
End Function

' // The binary logarithm of a real number
Public Function Log2(ByVal Value As Double) As Double
    Log2 = Log(Value) / 0.693147180559945
End Function

' // Rounding up
Public Function Ceil(ByVal Value As Double) As Double
    Ceil = -Int(-Value)
End Function

' // Rounding down (Int)
Public Function Floor(ByVal Value As Double) As Double
    Floor = Int(Value)
End Function

' // Secant of a real number
Public Function Sec(ByVal Value As Double) As Double
    Sec = 1 / Cos(Value)
End Function

' // Cosecant of a real number
Public Function Csc(ByVal Value As Double) As Double
    Csc = 1 / Sin(Value)
End Function

' // Cotangent of a real number
Public Function Ctg(ByVal Value As Double) As Double
    Ctg = 1 / Tan(Value)
End Function

' // Arcsine of a real number
Public Function Asin(ByVal Value As Double) As Double
    If Value = -1 Then Asin = -PI2: Exit Function
    If Value = 1 Then Asin = PI2: Exit Function
    Asin = Atn(Value / Sqr(-Value * Value + 1))
End Function

' // Arccosine of a real number
Public Function Acos(ByVal Value As Double) As Double
    If CSng(Value) = -1# Then Acos = PI: Exit Function
    If CSng(Value) = 1# Then Acos = 0: Exit Function
    Acos = Atn(-Value / Sqr(-Value * Value + 1)) + 2 * Atn(1)
End Function

' // Arcsecant of a real number
Public Function Asec(ByVal Value As Double) As Double
    Asec = 1.5707963267949 - Atn(Sgn(Value) / Sqr(Value * Value - 1))
End Function

' // Arccosecant of a real number
Public Function Acsc(ByVal Value As Double) As Double
    Acsc = Atn(Sgn(Value) / Sqr(Value * Value - 1))
End Function

' // Returns the angle whose tangent is the ratio of the two numbers
Public Function Atan2(ByVal Y As Double, ByVal X As Double) As Double
    If Y > 0 Then
        If X >= Y Then
            Atan2 = Atn(Y / X)
        ElseIf X <= -Y Then
            Atan2 = Atn(Y / X) + PI
        Else
            Atan2 = PI / 2 - Atn(X / Y)
        End If
    Else
        If X >= -Y Then
            Atan2 = Atn(Y / X)
        ElseIf X <= Y Then
            Atan2 = Atn(Y / X) - PI
        Else
            Atan2 = -Atn(X / Y) - PI / 2
        End If
    End If
End Function

' // Arccotangent of a real number
Public Function Actg(ByVal Value As Double) As Double
    Actg = 1.5707963267949 - Atn(Value)
End Function

' // Hyperbolic sine of a real number
Public Function Sinh(ByVal Value As Double) As Double
    Sinh = (Exp(Value) - Exp(-Value)) / 2
End Function

' // Hyperbolic cosine of a real number
Public Function Cosh(ByVal Value As Double) As Double
    Cosh = (Exp(Value) + Exp(-Value)) / 2
End Function

' // Hyperbolic tangent of a real number
Public Function Tanh(ByVal Value As Double) As Double
    Tanh = (Exp(2 * Value) - 1) / (Exp(2 * Value) + 1)
End Function

' // Hyperbolic cotangent of a real number
Public Function Ctgh(ByVal Value As Double) As Double
    Ctgh = 1 / (Exp(2 * Value) + 1) / (Exp(2 * Value) - 1)
End Function

' // Hyperbolic secant of a real number
Public Function Sech(ByVal Value As Double) As Double
    Sech = 2 / (Exp(Value) + Exp(-Value))
End Function

' // Hyperbolic cosecant of a real number
Public Function Csch(ByVal Value As Double) As Double
    Csch = 2 / (Exp(Value) - Exp(-Value))
End Function

' // Hyperbolic arcsine of a real number
Public Function Asinh(ByVal Value As Double) As Double
    Asinh = Log(Value + Sqr(Value * Value + 1))
End Function

' // Hyperbolic arcosine of a real number
Public Function Acosh(ByVal Value As Double) As Double
    Acosh = Log(Value + Sqr(Value * Value - 1))
End Function

' // Hyperbolic arctangent of a real number
Public Function Atanh(ByVal Value As Double) As Double
    Atanh = Log((1 + Value) / (1 - Value)) / 2
End Function

' // Hyperbolic arccotangent of a real number
Public Function Actan(ByVal Value As Double) As Double
    Actan = Log((Value + 1) / (Value - 1)) / 2
End Function

' // Hyperbolic arcsecant of a real number
Public Function Asech(ByVal Value As Double) As Double
    Asech = Log((Sqr(-Value * Value + 1) + 1) / Value)
End Function

' // Hyperbolic arccosecant of a real number
Public Function Acsch(ByVal Value As Double) As Double
    Acsch = Log((Sgn(Value) * Sqr(Value * Value + 1) + 1) / Value)
End Function

' // Return maximum of two numbers
Public Function Max(ByVal Op1 As Double, ByVal Op2 As Double) As Double
    Max = IIf(Op1 > Op2, Op1, Op2)
End Function

' // Return maximum of three numbers
Public Function Max3(ByVal Op1 As Double, ByVal Op2 As Double, ByVal Op3 As Double) As Double
    Max3 = IIf(Op1 > Op2, IIf(Op1 > Op3, Op1, Op3), IIf(Op2 > Op3, Op2, Op3))
End Function

' // Return maximum of four numbers
Public Function Max4(ByVal Op1 As Double, ByVal Op2 As Double, ByVal Op3 As Double, ByVal Op4 As Double) As Double
    Max4 = Max(Max3(Op1, Op2, Op3), Op4)
End Function

' // Return minimum of two numbers
Public Function Min(ByVal Op1 As Double, ByVal Op2 As Double) As Double
    Min = IIf(Op1 < Op2, Op1, Op2)
End Function

' // Return minimum of three numbers
Public Function Min3(ByVal Op1 As Double, ByVal Op2 As Double, ByVal Op3 As Double) As Double
    Min3 = IIf(Op1 < Op2, IIf(Op1 < Op3, Op1, Op3), IIf(Op2 < Op3, Op2, Op3))
End Function

' // Return minimum of four numbers
Public Function Min4(ByVal Op1 As Double, ByVal Op2 As Double, ByVal Op3 As Double, ByVal Op4 As Double) As Double
    Min4 = Min(Min3(Op1, Op2, Op3), Op4)
End Function

' // Returns the remainder of dividing one specified number by another specified number.
Public Function IEEERemainder(ByVal Op1 As Double, ByVal Op2 As Double) As Double
    IEEERemainder = Op1 - (Op2 * Round(Op1 / Op2))
End Function

' // Returns the remainder of dividing one specified number by another specified number.
Public Function rMod(ByVal Op1 As Double, ByVal Op2 As Double) As Double
    rMod = (Abs(Op1) - (Abs(Op2) * (Int(Abs(Op1) / Abs(Op2))))) * Sgn(Op1)
End Function