how to convert digit in 16 base to base 10.

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1.00/5 (1 vote)

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I have posted a few questions lately about PI, and C# math, and i almost there, but i need to ask one last question.

I figured out how to calculate PI, only to realize this is not what i needed for you can only go so far with that. Then I found out you can calculate PI to a digit of your choice with the BBP Formula.

My problem is the BBP is in 16 base and i need this number in 10 base.
My current code looks like this:

C#

double pi = 0;
for (int k = 0; k <=25; k++)
{
    pi = Math.Pow(16.0,-k) *
    ((4.0/(8*k+1.0))-
    (2.0/(8*k+4.0))-
    (1.0/(8*k+5.0))-
    (1.0/(8*k+6.0)));
    Console.WriteLine(pi.ToString());
}
Console.WriteLine("Press any key to continue...");
Console.ReadKey(true);

And the out put of this code is below:

5.06722085385879E-06
1.8789290093772E-07
7.76775121517736E-09
3.44793293050862E-10
1.6091877155537E-11
7.79570295400102E-13
3.88711525990975E-14
1.98322539359813E-15
1.03097121697889E-16
5.44347406057178E-18
2.91211179438419E-19
1.57549800977008E-20
8.60692632700397E-22
4.74204674455623E-23
2.63228669401317E-24
1.47090939027733E-25
8.2683300282764E-27
4.67271101635284E-28
2.65348590144992E-29
1.51345479607531E-30
8.66682856034781E-32
4.98130681533109E-33
2.87270191974158E-34
Press any key to continue...

So now here is the place i am stuck at.
How in the world do i get those long decimal numbers to turn into "1415926535897932384626433".

Thanks once again!

Posted 30-Apr-11 21:52pm

thexcodec

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Richard MacCutchan · Answer 1 · 2011-05-01T02:31:00

Solution 3

Those are not base 16 numbers, they are base 10 (decimal) numbers displayed in scientific notation. Use the String.Format() method to display in the format that you require.

Posted 1-May-11 2:31am

Richard MacCutchan

Comments

Sergey Alexandrovich Kryukov 1-May-11 16:07pm

Correct, a 5. It looks like OP does not understand how numbers are represented in principle.
--SA

jesusangelkdt · Answer 2 · 2011-04-30T23:46:00

Hi again texcodec, i used this and I get correct values, no need to change the base.

3,13333333333333
0,00808913308913309
0,000164923924115101
5,06722085385879E-06
1,8789290093772E-07
7,76775121517736E-09
3,44793293050862E-10
1,6091877155537E-11
7,79570295400102E-13
3,88711525990975E-14
Press any key to continue...

or better pi += to get the agregate value of every calculation.

3,13333333333333
3,14142246642247
3,14158739034658
3,14159245756744
3,14159264546034
3,14159265322809
3,14159265357288
3,14159265358897
3,14159265358975
3,14159265358979
3,14159265358979
3,14159265358979
3,14159265358979
3,14159265358979
3,14159265358979
3,14159265358979
Math.PI ->3,14159265358979
Press any key to continue...

I see 2 thing about this method:

1-. k is no equal to nth digit of pi, I mean with k=1 you get 3 correct decimal of pi, with k=2 -> 4, with k=3 -> 6, k=4 -> 7, so if you ask for a number of digit this is not directly the number of for to execute.
2-.With k>9 the double value is not enough to show such precission, so you'll get as better as Math.PI.

The class I linked you in the other post give pi as a string, and I thing that in every bucle you get a new digit, appending it to existing pi string, so the number of bucle (k) gives you the nth digit.

So seeing your code you got the formula working correctly, congratulations.

Regards

*dan!sh* · Answer 3 · 2011-04-30T22:25:00

Solution 1

You can convert base 16 number to base 10 using Convert.ToInt32 method. It has an overload where you can give the input as a string and base as a number. Like this:

int number = Convert.ToInt32("base 16 number", 16);

Update: Misunderstood the question. This time probably got it. :)

Following works fine for me.

double.Parse("exponential number as string here", System.Globalization.NumberStyles.Any);

If it still doesn't for you, then you may have to use string representation of the numbers for display.

Posted 30-Apr-11 22:25pm

dan!sh

Updated 1-May-11 18:42pm

v2

Comments

Sergey Alexandrovich Kryukov 1-May-11 16:11pm

What happened to you? It won't even execute, will throw exception. Correct answer was by Richard.
It's "1". Probably you mean something else; so I'll re-vote if you have to say something meaningful here. Alternatively, remove it.
Sorry,
--SA

dan!sh 2-May-11 0:24am

OP asked how to convert hexadecimal to decimal, if not I misunderstood the question. The above code will work. Here is the MSDN reference: here[^] and here[^].

dan!sh 2-May-11 0:26am

I now understand that OP is confused between exponential notation and hexadecimal numbers. Updated the reply.

Sergey Alexandrovich Kryukov 2-May-11 1:22am

Oh, is it just pseudo-code (in "")? You should explain that in your answer...
--SA

Sergey Alexandrovich Kryukov 2-May-11 1:25am

Correct answer is: nothing needs to be "converted".
As to OP's confusion... hard to say... it looks like 1) there is not full understanding of the fact that the notion hex or decimal have nothing to do with numeric types, only related to string representation, 2) failure to understand decimal exponential notation.
--SA