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Re: Mathematics, Java, good enough

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On 17/05/16 12:56, Nigel Wade wrote:
> On 17/05/16 11:49, Duncan Idaho wrote:
>> Hello again
>>
>> I have a question that involves mathematics. I agree that it's off topic but as I am writing in Java
>> I thought I'd give it a go (tenuous I know but it's the best I've got).
>>
>> I'm dredging up set theory from the furthest reaches of my memory. I'll probably get it wrong.
>> Homework? If only, that would mean I could have the last 50 years again ... perhaps not. %-)
>>
>> Anyway
>>
>> I have a set of characters S of cardinality C
>> example
>> if S = {a..z, 0..9, A..Z} then C = er, um  ..,62.
>>
>> For any given result string X, X need not be a set.
>>
>> eg if L = 8 then
>> "abcdefgh", "AAAAAAAA", "AABBCCDD" are all valid values for X
>>
>> how many strings of length L are possible from S
>>
>> I don't even know what to call the question and I probably won't understand the answer but it will be fun trying.
>>
>
> The answer is pretty simple. 62^8.
> The reasoning is also pretty simple.

Well strangely enough I did try that but according to my Ubuntu desktop calculator
62^8 is 2.183401056×10^14

I think that means move the decimal point 14 places to the right which gives
218340105600000 or 218,340,105,600,000 which I think is (deep breath)

two hundred and eighteen trillion three hundred and forty billion one hundred and five million six hundred thousand

8 character strings and I thought it must be wrong, that's an *huge* number

Is this correct

Thanks to you both for taking the time to reply

Idaho


>
> The first character has 62 possibilities.
> The second character also has 62 possibilities, so the first 2 characters have 62*62 possibilities (62^2)
> The third character also has 62 possibilities, so the first 3 characters have 62*62*62 possibilities (62^3)
> In general, for L from S, the number of possibilities is S^L.
>
> If you are not convinced, then just remove the letters and work with the numbers.
> The first digit can be 0-9. The second digit can be 0-9, so the allowed values are 00-99. And so on. This ought to be quite
> familiar. For 8 digits the range of possibilities would be 00000000-99999999.
>
>
> I'm not sure of the specific name is, most likely combination of probabilities.
>
>
>


-- 
Duncan Idaho
!(ghola mentat)

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Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 11:49 +0100
  Re: Mathematics, Java, good enough Eric Douglas <e.d.programmer@gmail.com> - 2016-05-17 04:55 -0700
  Re: Mathematics, Java, good enough Nigel Wade <nmw@ion.le.ac.uk> - 2016-05-17 12:56 +0100
    Re: Mathematics, Java, good enough Nigel Wade <nmw@ion.le.ac.uk> - 2016-05-17 13:06 +0100
    Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 13:29 +0100
      Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 09:54 -0400
        Re: Mathematics, Java, good enough FredK <fred.l.kleinschmidt@gmail.com> - 2016-05-17 07:17 -0700
          Re: Mathematics, Java, good enough FredK <fred.l.kleinschmidt@gmail.com> - 2016-05-17 07:29 -0700
            Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 10:58 -0400
              Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 18:10 +0100
                Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 14:02 -0400
                Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 14:10 -0400
                Re: Mathematics, Java, good enough Eric Douglas <e.d.programmer@gmail.com> - 2016-05-17 11:36 -0700
                Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 16:12 -0400
                Re: Mathematics, Java, good enough Eric Douglas <e.d.programmer@gmail.com> - 2016-05-17 13:56 -0700
                Re: Mathematics, Java, good enough Gene Wirchenko <genew@telus.net> - 2016-05-17 14:13 -0700
                Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-18 05:06 +0100
  Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 08:25 -0400
  Re: Mathematics, Java, good enough Martin Gregorie <martin@address-in-sig.invalid> - 2016-05-17 12:24 +0000
  Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 18:15 +0100
    Re: Mathematics, Java, good enough Jerry Stuckle <jstucklex@attglobal.net> - 2016-05-17 13:33 -0400
    Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 14:09 -0400
      Re: Mathematics, Java, good enough Gene Wirchenko <genew@telus.net> - 2016-05-17 14:17 -0700
        Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 17:49 -0400

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