RosettaCodeData/Task/Pi/PowerShell/pi-1.psh

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Function Get-Pi ( $Digits )
{
$Big = [bigint[]](0..10)
$ndigits = 0
$Output = ""
$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
$Output += [string]$n + '.'
$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 )
{
While ( $ndigits % 100 -ne 0 -or -not $Output )
{
If ( $Big[4] * $q + $r - $t -lt $n * $t )
{
$Output += [string]$n
$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
}
}
$Output
$Output = ""
}
}