2016 Update

Task/Fibonacci-sequence/PowerShell/fibonacci-sequence-1.psh

@@ -1,26 +1,9 @@
-function fib ($n) {
-    if ($n -eq 0) { return 0 }
-    if ($n -eq 1) { return 1 }
-
-    $m = 1
-    if ($n -lt 0) {
-        if ($n % 2 -eq -1) {
-            $m = 1
-        } else {
-            $m = -1
-        }
-
-        $n = -$n
+function FibonacciNumber ( $count )
+{
+    $answer = @(0,1)
+    while ($answer.Length -le $count)
+    {
+        $answer += $answer[-1] + $answer[-2]
     }
-
-    $a = 0
-    $b = 1
-
-    for ($i = 1; $i -lt $n; $i++) {
-        $c = $a + $b
-        $a = $b
-        $b = $c
-    }
-
-    return $m * $b
+    return $answer
 }

Task/Fibonacci-sequence/PowerShell/fibonacci-sequence-2.psh

@@ -1,8 +1,4 @@
-function fib($n) {
-    switch ($n) {
-        0            { return 0 }
-        1            { return 1 }
-        { $_ -lt 0 } { return [Math]::Pow(-1, -$n + 1) * (fib (-$n)) }
-        default      { return (fib ($n - 1)) + (fib ($n - 2)) }
-    }
-}
+$count = 8
+$answer = @(0,1)
+0..($count - $answer.Length) | Foreach { $answer += $answer[-1] + $answer[-2] }
+$answer

Task/Fibonacci-sequence/PowerShell/fibonacci-sequence-3.psh

@@ -0,0 +1,8 @@
+function fib($n) {
+    switch ($n) {
+        0            { return 0 }
+        1            { return 1 }
+        { $_ -lt 0 } { return [Math]::Pow(-1, -$n + 1) * (fib (-$n)) }
+        default      { return (fib ($n - 1)) + (fib ($n - 2)) }
+    }
+}