For one, you're missing a curly before "SPECIAL".  But I think you rather want 

$simulations[$simulation_index]->{"SPECIAL"} = [ sort {$$a[0] <=> $$b[
+0] } @{$simulations[$simulation_index]->{"SPECIAL"} } ];

[download]

i.e., the anonymous array [ ... ] would correspond to your original \@sorted.

What you have is a reference to a hashref (\{ ... }), where the anonymous hash complains when initialized with an odd number of elements from the sort results.

In reply to Re: Odd number of elements in anon hash by almut
in thread Odd number of elements in anon hash by roibrodo

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