PowerShell/Docs/list-pi.md

## Script: *list-pi.ps1*

This PowerShell script calculates and lists the digits of the mathematical constant PI.

## Parameters
```powershell
list-pi.ps1 [[-Digits] <Int32>] [<CommonParameters>]

-Digits <Int32>
    Specifies the number of digits to list (1000 by default)
    
    Required?                    false
    Position?                    1
    Default value                1000
    Accept pipeline input?       false
    Accept wildcard characters?  false

[<CommonParameters>]
    This script supports the common parameters: Verbose, Debug, ErrorAction, ErrorVariable, WarningAction, 
    WarningVariable, OutBuffer, PipelineVariable, and OutVariable.
```

## Example
```powershell
PS> ./list-pi
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342...

```

## Notes
Author: Markus Fleschutz | License: CC0

## Related Links
https://github.com/fleschutz/PowerShell

## Script Content
```powershell
<#
.SYNOPSIS
	Lists PI
.DESCRIPTION
	This PowerShell script calculates and lists the digits of the mathematical constant PI.
.PARAMETER digits
	Specifies the number of digits to list (1000 by default)
.EXAMPLE
	PS> ./list-pi
	3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342...
.LINK
	https://github.com/fleschutz/PowerShell
.NOTES
	Author: Markus Fleschutz | License: CC0
#>

param([int]$Digits = 1000)

function List-Pi ( $Digits ) {
	$Big = [bigint[]](0..10)
 
	$ndigits = 0
 
 	$q = $t = $k = $Big[1]
 	$r =           $Big[0]
	$l = $n =      $Big[3]

	# calculate first digit
	$nr = ( $Big[2] * $q + $r ) * $l
	$nn = ( $q * ( $Big[7] * $k + $Big[2] ) + $r * $l ) / ( $t * $l )
	$q *= $k
	$t *= $l
	$l += $Big[2]
	$k = $k + $Big[1]
	$n = $nn
	$r = $nr
 
 	Write-Host "$($n)." -noNewline
 	$ndigits++
 
 	$nr = $Big[10] * ( $r - $n * $t )
 	$n = ( ( $Big[10] * ( 3 * $q + $r ) ) / $t ) - 10 * $n
 	$q *= $Big[10]
 	$r = $nr
 
 	while ($ndigits -lt $Digits) {
		if ($Big[4] * $q + $r - $t -lt $n * $t) {
			Write-Host "$n" -noNewline
			$ndigits++
			$nr = $Big[10] * ( $r - $n * $t )
			$n = ( ( $Big[10] * ( 3 * $q + $r ) ) / $t ) - 10 * $n
			$q *= $Big[10]
			$r = $nr
		} else {
			$nr = ( $Big[2] * $q + $r ) * $l
			$nn = ( $q * ( $Big[7] * $k + $Big[2] ) + $r * $l ) / ( $t * $l )
			$q *= $k
			$t *= $l
			$l += $Big[2]
			$k = $k + $Big[1]
			$n = $nn
			$r = $nr
		}
      }
	Write-Host "...  ($Digits digits)"
}

try {
	List-Pi $Digits
	exit 0 # success
} catch {
	"⚠️ Error in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
	exit 1
}
```

*(generated by convert-ps2md.ps1 using the comment-based help of list-pi.ps1 as of 07/29/2023 09:55:12)*