[R-pkg-devel] [External] Re: incomplete gamma function Fortran subroutine

Looking at this section of WRE may help:

https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Numerical
-analysis-subroutines


Best,

luke

On Tue, 21 Jul 2020, Wang, Zhu wrote:

Thanks to Ben and John. Perhaps the program should call pgamma in R 
and pass the number to Fortran. Calling some Fortran subroutines 
older than R can trigger concerns when submitting the package to the 
CRAN.

Best,
Zhu

-----Original Message-----
From: John P. Nolan <jpnolan at american.edu>
Sent: Tuesday, July 21, 2020 1:43 PM
To: Wang, Zhu <wangz1 at uthscsa.edu>; Ben Bolker <bbolker at gmail.com>; 
r-package-devel at r-project.org
Subject: RE: [R-pkg-devel] incomplete gamma function Fortran 
subroutine

As others have said, built-in function pgamma is a (normalized) 
version of the incomplete gamma function!?? John

-----Original Message-----
From: R-package-devel <r-package-devel-bounces at r-project.org> On 
Behalf Of Wang, Zhu
Sent: Tuesday, July 21, 2020 2:16 PM
To: Ben Bolker <bbolker at gmail.com>; r-package-devel at r-project.org
Subject: Re: [R-pkg-devel] incomplete gamma function Fortran 
subroutine

External Email: Use caution with links and attachments.

Sorry for not making myself clear: The Fortran subroutine in an R 
package needs to call incomplete gamma function.

-----Original Message-----
From: R-package-devel <r-package-devel-bounces at r-project.org> On 
Behalf Of Ben Bolker
Sent: Tuesday, July 21, 2020 12:54 PM
To: r-package-devel at r-project.org
Subject: Re: [R-pkg-devel] incomplete gamma function Fortran 
subroutine

??? Is there a reason not to use pgamma(), possibly adjusted by a 
(de-)normalizing constant??? (See detailed notes in ?pgamma)

On 7/21/20 1:44 PM, Wang, Zhu wrote:

Hello,

In an R function within a package, I would like to call a Fortran 
subroutine to compute lower gamma function. Any advice will be 
appreciated.

Thanks!

Zhu Wang

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