Cumulative standard deviation: Difference between revisions

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 =={{header|Raku}}==
 (formerly Perl 6)
-{{works with|Rakudo Star|2010.08}}
 Using a closure:
 <syntaxhighlight lang="raku" line>sub sd (@a) {
     my $mean = @a R/ [+] @a;
-    sqrt @a R/ [+] map (* - $mean)**2, @a;
+    sqrt @a R/ [+] map (* - $mean)², @a;
 }
@@ Line 3,638: / Line 3,638: @@
 say f $_ for 2, 4, 4, 4, 5, 5, 7, 9;</syntaxhighlight>
-Using a state variable:
+Using a state variable (remember that <tt><(x-<x>)²> = <x²> - <x>²</tt>):
-<syntaxhighlight lang="raku" line># remember that <(x-<x>)²> = <x²> - <x>²
+<syntaxhighlight lang="raku" line>sub stddev($x) {
-sub stddev($x) {
     sqrt
-        (.[2] += $x**2) / ++.[0] -
+        ( .[2] += $x²) / ++.[0]
-        ((.[1] += $x) / .[0])**2
+      - ((.[1] += $x ) /   .[0])²
     given state @;
 }
-say stddev $_ for <2 4 4 4 5 5 7 9>;</syntaxhighlight>
+say .&stddev for <2 4 4 4 5 5 7 9>;</syntaxhighlight>
 {{out}}