Get-PercentageDifference

Get-PercentageDifference.ps1

# An advanced version of this script is now in my scripts collection:
# https://github.com/TheFreeman193/Scripts/blob/main/PowerShell/Tools/Get-RelativeDifference/Get-RelativeDifference.ps1

Function Get-PercentageDifference {
    <#
    .SYNOPSIS
    Calculates percentage difference.

    .DESCRIPTION
    Calculates percentage difference between two values,
    $A and $B, to the precision specified by $Precision.

    .PARAMETER A
    The first value to compare against

    .PARAMETER B
    The second value to compare against

    .PARAMETER Precision
    Level of precision (digits). Default = 2

    .INPUTS
    None. Get-PercentageDifference does not accept pipeline input.

    .OUTPUTS
    System.String. Get-PercentageDifference returns a string
    representation of the percentage diffence.

    .EXAMPLE
    PS> Get-PercentageDifference -A 15 -B 30
    66.67%

    .EXAMPLE
    PS> Get-PercentageDifference 15 30
    66.67%

    .EXAMPLE
    PS> $First, $Second = -154, 12
    PS> gpd $First $Second 5
    233.80282%
    #>

    [CmdletBinding(ConfirmImpact = 'None')]
    [Alias('Get-PercentDiff', 'gpd')]
    param(
        [Parameter(Mandatory, Position = 0)]
        [Alias('X')]
        [Int64]
        $A,

        [Parameter(Mandatory, Position = 1)]
        [Alias('Y')]
        [Int64]
        $B,

        [Parameter(Position = 2)]
        [Alias('P')]
        [UInt16]
        $Precision = 2
    )
    # Format as a % to $Precision digits
    "{0:P$Precision}" -f (
        # Formula: 2 * |A - B| / |A + B|
        2 * [math]::Abs($A - $B) /
        [math]::Abs($A + $B)
    )
}