Need to compress a large number into a Smaller number

[godonga]

Hi
This question may sound wierd but I really need you help. I need to come up with a program that takes in at least a 16 digit number and outputs say a 6 digit number. I should be able to do the reverse as well i.e. put in the 6 digit number and output the exact 16 digit number.

Any ideas?

G

 

[ArkM]

Compress? Is it possible to compress 12345678 to 6-digit number?
May be input or output numbers with fixed precision?
Please, pose a question with sufficient precision...

 

[xwb]

16 decimal digits is appx 53 bits. Say 54 bits. If we divide that by 6, we get 9 so each digit is 9 bits i.e. it has a range of 0..511.

If you take a base 512 number similar to what they do in uuencode, you should be able to get it into 6 base 512 numbers. All you have to figure out is which characters to use to represent 0..511.

 

[ArkM]

54 == 6*9; to represent 0..511 we need 9 bits...
Or funny compress method?...
I suspect it was a question about proper format specifications or stream manipulators. May be I'm wrong...

 

[godonga]

Thanks guys for all your input. The logic of this would be to have something like a failed implementation of MD5 where one can get the original number from the hash message. the following is an example of what I am looking for


12345678912345678919 --> f(x) --> 234679

37677772399998633091 --> f(x) --> 346723

234679 --> f(x) --> 12345678912345678919

346723 --> f(x) --> 37677772399998633091

The resultant must'nt be limited to an Integer , it can be anything as long as it be reconverted to Integer in the reverse.

Your thoughts???

 

[xwb]

Hashing is different. It is based on a few slots and a wide range of numbers, knowing full well that all the slots will never be filled and all the numbers will never be requested.