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https://issues.apache.org/jira/browse/STATISTICS-31?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17380823#comment-17380823
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Benjamin W Trent commented on STATISTICS-31:
--------------------------------------------

Yes, that is what I am suggesting. 

 

I have already began poking around here: 
[https://github.com/benwtrent/commons-statistics/pull/1/files]

I am going to add more tests that exploit the `1-cdf` issue and tweak the 
overrides to be more accurate. 

 

Obviously, this is a draft and a WIP. Once ready, I will open a PR against the 
repo's trunk.

> 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
>
> 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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