Arithmetic derivative: Difference between revisions

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@@ Line 238: / Line 238: @@
 use bigint;
 no warnings 'uninitialized';
-use List::Util <sum max>;
+use List::Util 'max';
 use ntheory 'factor';
@@ Line 244: / Line 244: @@
 sub D ($n) {
-    my %f;
+    my(%f, $s);
-    return 0 if $n == 0;
+    $f{$_}++ for factor max 1, my $nabs = abs $n;
-    $f{$_}++ for factor (my $nabs = abs $n);
+    map { $s += $nabs * $f{$_} / $_ } keys %f;
-    my $s = sum map { $nabs * $f{$_} / $_  } keys %f;
     $n > 0 ? $s : -$s;
 }