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https://issues.apache.org/jira/browse/STATISTICS-31?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17383269#comment-17383269
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Benjamin W Trent commented on STATISTICS-31:
--------------------------------------------

[~aherbert]

 

Wolfram does have survival + cdf support for those distributions.

 

It seems to me that the current PR though is plenty big enough as it is (800 
LOC). Do we really want to make this PR even larger?

> Add survival probability function to continuous distributions
> -------------------------------------------------------------
>
>                 Key: STATISTICS-31
>                 URL: https://issues.apache.org/jira/browse/STATISTICS-31
>             Project: Apache Commons Statistics
>          Issue Type: New Feature
>            Reporter: Benjamin W Trent
>            Priority: Major
>          Time Spent: 40m
>  Remaining Estimate: 0h
>
> It is useful to know the [survival 
> function|[https://en.wikipedia.org/wiki/Survival_function]] of a number given 
> a continuous distribution.
> While this can be approximated with
> {noformat}
> 1 - cdf(x){noformat}
> , there is an opportunity for greater accuracy in certain distributions.
>  
> A good example of this is the gamma distribution. The survival function for 
> that distribution would probably look similar to:
>  
> ```java
> @Override
>  public double survivalProbability(double x) {
>      if (x <= SUPPORT_LO)
> {         return 1;     }
> else if (x >= SUPPORT_HI)
> {         return 0;     }
>     return RegularizedGamma.Q.value(shape, x / scale);
>  }
> ```
>  



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