Hi, I am a FORTRAN developer and I am 'translating' R functions in FORTRAN subroutines. I am 'new' to R. It's my first question in this mailing-list and English is not my natural language. Very often, an R function gives an 'array' as result and you don't have to bother with the dimension of the array : R creates automatically an array with the good length. It's not really the case with FORTRAN. I call FORTRAN subroutines with .fortran(). Until now, I create an array with the 'max' dimensions in R, give it to FORTRAN; FORTRAN updates the array and R retrieves it. But calculating the 'max' before calling the FORTRAN subroutine can be complicated. Is it possible to create a 'new' array in a FORTRAN subroutine and to make it be read by R ? Or is it possible to have a 'pointer' in R, to give it to the FORTRAN subroutine where an ALLOCATE can create the array and then R works with the array ? The other solution, is to work with dummies dimension in FORTRAN (REAL*8 array1(*)) but can R work with that ? TIA Jean -------------- next part -------------- Ce message et toutes les pi?ces jointes (ci-apr?s le 'Message') sont ?tablis ? l'intention exclusive des destinataires et les informations qui y figurent sont strictement confidentielles. Toute utilisation de ce Message non conforme ? sa destination, toute diffusion ou toute publication totale ou partielle, est interdite sauf autorisation expresse. Si vous n'?tes pas le destinataire de ce Message, il vous est interdit de le copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie. Si vous avez re?u ce Message par erreur, merci de le supprimer de votre syst?me, ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque support que ce soit. Nous vous remercions ?galement d'en avertir imm?diatement l'exp?diteur par retour du message. Il est impossible de garantir que les communications par messagerie ?lectronique arrivent en temps utile, sont s?curis?es ou d?nu?es de toute erreur ou virus. ____________________________________________________ This message and any attachments (the 'Message') are intended solely for the addressees. The information contained in this Message is confidential. Any use of information contained in this Message not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval. If you are not the addressee, you may not copy, forward, disclose or use any part of it. If you have received this message in error, please delete it and all copies from your system and notify the sender immediately by return message. E-mail communication cannot be guaranteed to be timely secure, error or virus-free.
On 04/03/2016 3:34 AM, MAURICE Jean - externe wrote:> Hi, > I am a FORTRAN developer and I am 'translating' R functions in FORTRAN subroutines. I am 'new' to R. It's my first question in this mailing-list and English is not my natural language. > > Very often, an R function gives an 'array' as result and you don't have to bother with the dimension of the array : R creates automatically an array with the good length. It's not really the case with FORTRAN. I call FORTRAN subroutines with .fortran(). > > Until now, I create an array with the 'max' dimensions in R, give it to FORTRAN; FORTRAN updates the array and R retrieves it. But calculating the 'max' before calling the FORTRAN subroutine can be complicated. Is it possible to create a 'new' array in a FORTRAN subroutine and to make it be read by R ?I don't think this is possible in pure Fortran, but it is certainly possible in C or C++ code. You need to call the external routine using .Call() instead of .C or .Fortran. See the section 5.9 of the Writing R Extensions manual for details.> Or is it possible to have a 'pointer' in R, to give it to the FORTRAN subroutine where an ALLOCATE can create the array and then R works with the array ?No. R needs to manage allocations of all the objects it uses. However, if you never need to use these arrays in R code (you just want R to keep references to them to pass to other external routines), you can (in C or C++) use the external pointer type. I don't think there's any support for that in Fortran.> The other solution, is to work with dummies dimension in FORTRAN (REAL*8 array1(*)) but can R work with that ?No, for the same reason. Duncan Murdoch
Hi,
Until you get a more definitive answer, I will make an attempt to give some
advice.
When using an assumed sized array (i.e. REAL*8 array1(*)) you still need to
allocate the memory prior to calling the Fortran subroutine, so you would still
need to know its maximum length.
Arrays created in a Fortran subroutine via the use of the ALLOCATE statements
are not simple arrays (in the sense of C like pointers), but are more akin to a
C structure, in that they also contain information concerning the size of the
array, stride etc. These structures are compiler dependent, their contents often
not clearly documented and subject to change. They are therefore not very good
for cross-language computing (or even cross-compiler computing).
To try and alleviate this the Fortran standard introduced C interoperability
(see https://gcc.gnu.org/onlinedocs/gfortran/Interoperability-with-C.html for
example) and I expect you are going to have to take a look at this in order to
pass memory allocated in your Fortran program back up to R. Care is going to
have be taken to make sure that the memory is deallocated when it has been
finished with (which is probably going to have to be done in Fortran).
The easiest way of getting all this to interact nicely with R is probably
through the R C API which is described in documents like
https://cran.r-project.org/doc/manuals/R-exts.pdf.
Martyn
-----Original Message-----
From: R-devel [mailto:r-devel-bounces at r-project.org] On Behalf Of MAURICE
Jean - externe
Sent: 04 March 2016 08:34
To: r-devel at r-project.org
Subject: [Rd] ALLOCATE in a FORTRAN subroutine
Hi,
I am a FORTRAN developer and I am 'translating' R functions in FORTRAN
subroutines. I am 'new' to R. It's my first question in this
mailing-list and English is not my natural language.
Very often, an R function gives an 'array' as result and you don't
have to bother with the dimension of the array : R creates automatically an
array with the good length. It's not really the case with FORTRAN. I call
FORTRAN subroutines with .fortran().
Until now, I create an array with the 'max' dimensions in R, give it to
FORTRAN; FORTRAN updates the array and R retrieves it. But calculating the
'max' before calling the FORTRAN subroutine can be complicated. Is it
possible to create a 'new' array in a FORTRAN subroutine and to make it
be read by R ?
Or is it possible to have a 'pointer' in R, to give it to the FORTRAN
subroutine where an ALLOCATE can create the array and then R works with the
array ?
The other solution, is to work with dummies dimension in FORTRAN (REAL*8
array1(*)) but can R work with that ?
TIA
Jean
________________________________________________________________________
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Hi Martyn, Many thanks for your answer. If I make it short : we can, once we know how to do it, 'drive' R from within FORTRAN for example to do a Myarray = seq(0, mydimension) in R once we have compute mydimension in FORTRAN. Is that correct ? If yes : it's too 'complicated' for the time I am hired (I mean I have been hired to do FORTRAN code not to learn R !). Second question : for what I have understood in r_exts, it's more 'efficient' to translate R routines in C rather than in FORTRAN (speed must be the 'same', but there are a lot more possibilities in C for the programmer) : right ? I do not know why my customer (client ?) wanted to translate some R routines in FORTRAN. May be it's by accident (in my humble opinion they even don't know about C). If you confirm this fact, I'll speak about C with my customer because we are at the very beginning of great works (great amounts of work ?) and I don't matter, I am also a skilled C programmer !! I hope you understand what I want to say, english is not my natural language ! Thanks again and best regards. Jean -------------- next part -------------- Ce message et toutes les pi?ces jointes (ci-apr?s le 'Message') sont ?tablis ? l'intention exclusive des destinataires et les informations qui y figurent sont strictement confidentielles. Toute utilisation de ce Message non conforme ? sa destination, toute diffusion ou toute publication totale ou partielle, est interdite sauf autorisation expresse. Si vous n'?tes pas le destinataire de ce Message, il vous est interdit de le copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie. Si vous avez re?u ce Message par erreur, merci de le supprimer de votre syst?me, ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque support que ce soit. Nous vous remercions ?galement d'en avertir imm?diatement l'exp?diteur par retour du message. Il est impossible de garantir que les communications par messagerie ?lectronique arrivent en temps utile, sont s?curis?es ou d?nu?es de toute erreur ou virus. ____________________________________________________ This message and any attachments (the 'Message') are intended solely for the addressees. The information contained in this Message is confidential. Any use of information contained in this Message not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval. If you are not the addressee, you may not copy, forward, disclose or use any part of it. If you have received this message in error, please delete it and all copies from your system and notify the sender immediately by return message. E-mail communication cannot be guaranteed to be timely secure, error or virus-free.