in reply to Converting binary to double precision

Your value comes from a big-endian system, so you'll need 'd>' to decode it:

$n = pack 'H16', '3f0df9673344c570';;

print unpack 'd>', $n;;
5.71713084433029e-005

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You could also do the byte swapping yourself:

$n = pack 'H16', '3f0df9673344c570';;

print unpack 'd', scalar reverse $n;;
5.71713084433029e-005

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Re^2: Converting binary to double precision (big-endian)
by ahoriuch (Acolyte) on Feb 24, 2014 at 21:34 UTC

    In my case, this was the correct answer. I needed to switch from big to little-endian. It's amazing how little there is on the internet on this subject. Hopefully this will help future users. 

    my $n = pack 'H16', '3f0df9673344c570';;

printf "Big\n";
print unpack ("d", scalar reverse $n);

#Big
#5.71713084433029e-05

printf "\nLittle\n";
print unpack ("d",$n);
printf "\n";

#Little
#1.69044404965372e+235

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[d/l]

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