# the arrays of zeros are now the keys
%haystack = reverse %haystack;

# supposed to search the keys for zero sets that only contain numbers within 0.0001 of an integer
my @wants = grep { / (.*\.0000.*)|(.*\.9999.*) / } keys %haystack; 
    
# supposed to print out the corresponding values from %haystack
print Dumper{ values of a, b, c corresponding to the elements of @wants };