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You will find many of the common mathematical functions are built into the Math. namespace. This page offers a few additional functions that are sometimes useful and provides examples of some lesser-known language features. For simplicity, I have included any required structures immediately after each function, however, structures are normally located after the End Class statement.
 
Extract decimal part of a number
Private Shared Function Get_Decimal_Part(ByVal dec As Double) As Double
Return (dec - Math.Floor(dec))
End Function

 
Convert Integer to Hex
Private Shared Function IntegerToHex(i As Integer) As String
Return Hex(i)
End Function

 
Convert Hex to Integer
Private Shared Function HexToInteger(h As String) As Integer
Return Convert.ToInt32(h.ToLower, 16)
End Function

 
Distance between two points
Private Shared Function Distance(x1 As Double, y1 As Double, x2 as Double, y2 as Double) As Double
Return Math.Sqrt(((x1 - x2) * (x1 - x2)) + ((y1 - y2 ) *(y1 - y2)))
End Function

 
Is Number a Prime
Caution - this only works for small numbers (up to a few thousand) because it is a slow process
 
Private Shared Function Is_Prime_Number(n As Integer) As Boolean
' Euclidian method much faster for huge numbers but on rare occassions, it gives wrong answer
' Euclidian method involves very advanced mathematics
' This function is not suitable for very large numbers
Dim ret As Boolean = True
n = Math.Abs(n)
If n < 4 Then Return True
If n Mod 2 = 0 Then Return False
Dim s As Integer = CInt(Math.Floor(Math.Sqrt(n)))
For i As Integer = 3 To s Step 2
If n Mod s = 0 Then
ret = False
Exit For
End If
Next
Return ret
End Function

 
Sum (Total)
Private Shared Function Sum(ListV As List(Of Double)) As Double
Return ListV.Sum
End Function

 
Mean (Average)
Private Shared Function Sum(ListV As List(Of Double)) As Double
Return ListV.Average
End Function

 
Median
Private Shared Function Median(ListV As List(Of Double)) As Double
Dim ret As Double
ListV.Sort()
ret = ListV.Item((ListV.Count - 1) \ 2)
If ListV.Count Mod 2 = 0 Then
ret = ListV.Item((ListV.Count - 1) \ 2)
ret += ListV.Item(ListV.Count \ 2)
ret /= 2
End If
Return ret
End Function

 
Mode
Private Shared Function Mode(ListValues As List(Of Double)) As Double
Return ListValues.GroupBy(Function(n) n).OrderByDescending(Function(g) g.Count).Select(Function(g) g.Key).FirstOrDefault
End Function

 
Variance
Private Shared Function Variance(ListV As List(Of Double)) As Double
Dim ret As Double = 0
For Each d As Double In ListV
ret += Math.Pow(d - ListV.Average, 2)
Next
ret /= ListV.Count
Return ret
End Function

 
Standard Deviation
Private Shared Function StandardDeviation(ListV As List(Of Double)) As Double
Dim ret As Double = 0
For Each d2 As Double In ListV
ret += Math.Pow(d2 - ListV.Average, 2)
Next
ret /= ListV.Count
Return Math.Sqrt(ret)
End Function

 
Percentile Value
Private Function PercentileValue(ListV As List(Of Double), percent As Double) As Double
Dim ret As Double = 0
ListV.Sort()
Dim i As Integer = Math.Round(ListV.Count * percent \ 100) - 1
If i >= 0 Then
ret = ListV(i)
End If
Return ret
End Function

 
Percentile
Private Shared Function Percentile(listV As List(Of Double), valu As Double) As Double
listV.Sort()
Dim ret As Double = 0
For i As Integer = 0 To listV.Count - 1
If listV.Item(i) >= valu Then
Exit For
End If
ret = 100 * (i + 1) / listV.Count
Next
Return ret
End Function

 
Greatest Common Denominator
VB.Net has a namespace dedicated to BigInteger arithmatic. If you are using huge mumbers or learning about basic encryption, you may find some answers in the Big Integer documentation.
 
Private Shared Function Greatest_Common_Denominator(n1 As Integer, n2 As Integer) As Integer
If n1 = 0 Or n2 = 0 Then Return 0
Dim min1 As Integer = Math.Min(n1, n2)
Dim max1 As Integer = Math.Max(n1, n2)
Dim lastMax1 As Integer = 0
While max1 <> lastMax1
lastMax1 = max1
max1 = max1 Mod min1
End While
Return max1
End Function

 
Lowest Common Multiple
This function uses the Greatest_Common_Denominator function, the approriate code is immediately above this example
 
Private Shared Function Lowest_Common_Multiple(n1 As Integer, n2 As Integer) As Integer
Return (n1 * n2) \ Greatest_Common_Denominator(n1, n2)
End Function

 
Degrees Minutes and Seconds
Public Shared Function DegMinSecToDeg(d As Double, Optional m As Double = 0, Optional s As Double = 0) As Double
Return d + (m / 60) + (s / 3600)
End Function
' Public Shared Function DegToDegMin(d As Double) As IntegerDouble
Dim ret As IntegerDouble
ret.i1 = CInt(Int(d))
ret.d1 = (d - CInt(Math.Floor(d))) * 60
Return ret
End Function
Public Structure IntegerDouble
Dim i1 As Integer
Dim d1 As Double
End Structure
'
Public Shared Function DegToDegMinSec(d As Double) As IntegerIntegerDouble
Dim ret As IntegerIntegerDouble
ret.i1 = CInt(Int(d))
d = (d - ret.i1) * 60
ret.i2 = CInt(Int(d))
ret.d1 = (d - ret.i2) * 60
Return ret
End Function
Public Structure IntegerIntegerDouble
Dim i1 As Integer
Dim i2 As Integer
Dim d1 As Double
End Structure

 
Temperature
Public Shared Function Celcius_To_Farenheit(ByVal value As Double) As Double
Return ((9 * value) + 160) / 5
End Function
'
Public Shared Function Farenheit_To_Celcius(ByVal value As Double) As Double
Return ((5 * value) - 160) / 9
End Function

 
Convert Percentage to Fraction
Private Shared Function GetFraction(percent As Integer) As Fraction
Dim frac1 As New Fraction
Dim i As Integer = 2
frac1.top = percent
frac1.bottom = 100
While i <= frac1.bottom
If (frac1.top Mod i = 0) And (frac1.bottom Mod i = 0) Then
frac1.top \= i ' the \ means integer division
frac1.bottom \= i ' the \ means integer division
Else
i += 1
End If
End While
Return frac1
End Function
Public Structure Fraction
Dim top As Integer
Dim bottom As Integer
End Structure

 
Convert Fraction to Percentage
Private Function GetPercent(fracTop As Integer, fracBottom as Integer) As Double
Return 100 * fracTop / fracBottom
End Function

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