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https://issues.apache.org/jira/browse/MAPREDUCE-1923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12892030#action_12892030
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Tsz Wo (Nicholas), SZE commented on MAPREDUCE-1923:
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I also have re-computed the bits at the 10^15 th position and obtained a longer
bit sequence.
{noformat}
Starting position: 1,000,000,000,000,001
Number of bits : 228 bits
Bit in Hex :
6216B069 CB6C1D36 117099E4 3646A6D4 48D887CC D95CC79A C84E60D2 3
{noformat}
The results agree with the ones posted in
[MAPREDUCE-637|https://issues.apache.org/jira/browse/MAPREDUCE-637?focusedCommentId=12725883&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12725883]
and [PiHex|http://oldweb.cecm.sfu.ca/projects/pihex/announce1q.html].
As usual, two computations were preformed as shown below.
|| Starting Position || Precision (in bits) || Time Used || CPU Time || Date
Completed ||
| 999,999,999,999,993 | 288 | 13 days | 248 years | July 2, 2010 |
| 1,000,000,000,000,001 | 256 | 25 days | 283 years | July 6, 2010 |
See also [the
note|https://issues.apache.org/jira/browse/MAPREDUCE-1923?focusedCommentId=12892027&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12892027]
in the previous comment.
> Support arbitrary precision in the distbbp example
> --------------------------------------------------
>
> Key: MAPREDUCE-1923
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1923
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: examples
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
> Priority: Minor
> Attachments: Mod1Fraction_IntArray.java
>
>
> The precision obtained by _distbbp_ is limited by Java {{double}} (IEEE 754
> 64-bit), which has machine epsilon e=2^(-53). When it is used to compute the
> 10^15 th bit of π, only 26-bit precision with 99.9999998% confident is
> obtained. (Will provide the error analysis later.) It would be great if it
> supports arbitrary precision arithmetics.
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