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<klobumFfoflU1@mid.individual.net> 1@dont-email.me> <kls9koF4ootU1@mid.individual.net>
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On 08.09.2023 14.52, db wrote:
> On 07.09.2023 11.49, db wrote:
>> On 06.09.2023 23.35, pehache wrote:
>>> Le 06/09/2023 ? 14:24, db a ?crit :
>>>> On 05.09.2023 11.50, pehache wrote:
>>>>> Le 04/09/2023 ? 16:43, db a ?crit :
>>>>>> I see that rather than try to convert a C++ function to
>>>>>> Fortran, it might be better to call it from a Fortran
>>>>>> program. So I found a description of how to do it
>>>>
>>>> It resulted in a Forytran program that calls a Fortran function
>>>> that calls the C++ function IBAND (exists as iband.cpp). Here is
>>>> the code (sorry for the length)
>>>>
>>>> module STUFF
>>>> integer, parameter :: dbl=selected_real_kind(14)
>>>> integer, parameter :: qud=selected_real_kind(30)
>>>> end module STUFF
>>>> program JBAND_TEST
>>>> use STUFF; implicit none
>>>>
>>>> real(dbl) :: curr, FORTJBAND
>>>> real(qud) :: tbar
>>>> do
>>>> read *, tbar
>>>> if (tbar < 0) exit
>>>> curr = FORTJBAND (tbar)
>>>> print `(" curr =", f10.4)`, curr
>>>> enddo
>>>> end program JBAND_TEST
>>>> function FORTJBAND (tbar)
>>>> use STUFF; implicit none
>>>> interface
>>>> function JBAND (tbar) bind(c)
>>>> import JBAND, c_long_double
>>>> import tbar, c_long_double
>>>> end function JBAND
>>>> end interface
>>>> real(dbl) :: FORTJBAND
>>>> real(qud) :: tbar, JBAND
>>>> FORTJBAND = JBAND (tbar)
>>>> end function FORTJBAND
>>>
>>> 1) You are missing the ISO_C_BINDING module
>>> 2) I don`t get the syntax with the "import"
>>> 3) you don`t need to declare JBAND in addition to the interface
>>>
>>> =======================================
>>> function FORTJBAND (tbar)
>>> use ISO_C_BINDING
>>> use STUFF
>>> implicit none
>>> interface
>>> function JBAND (tbar) bind(c)
>>> real(c_lonf_double) :: JBAND
>>> real(c_lonf_double) :: tbar
>>> end function JBAND
>>> end interface
>>> real(dbl) :: FORTJBAND
>>> real(qud) :: tbar
>>> FORTJBAND = JBAND (tbar)
>>> end function FORTJBAND
>>> =======================================
>>>
>>>>
>>>> I then wrote a script for running it, reproducing what the link
>>>> tells me:
>>>>
>>>> cpp -o jband.o jband.cpp
>>>> gfortran -o jbandtest.o jbandtest.f90
>>>> gfortran jband.o jbandtest.o
>>>> ./a.out << eoi
>>>> 1.0
>>>> 10.0
>>>> -1
>>>> eoi
>>>>
>>>> When I run this, I get this:
>>>>
>>>> ~/ownlib90/tests> ./jbandtest
>>>> cpp: fatal error: cannot execute `cc1plus`: execvp: No such file or
>>>> directory
>>>> compilation terminated.
>>>
>>> Isn`t "cpp" just the C/C++ preprocessor? Shouldn`t you use "g++"
>>> instead?
>>>
>> Ah, OK, I thought it mean c plus plus. I will install C++ now
>> and compile with G++ (i suppose).
>>
> I now have g++ installed and ran it with g++ instead of cpp. I still
> get complaints about long double:
>
> jbandtest.f90:21:31:
>
> 21 | import JBAND, c_long_double
> | 1
> Error: Cannot IMPORT `c_long_double` from host scoping unit at (1) -
> does not exist.
> jbandtest.f90:22:30:
>
> (several times). Is it the underscores? Inside the C++ function, it
> is just "long double".
I just tried reducing all long double entities to plain double in both
the C++ and calling Fortran units. Now it says that C_double does not
exist. So the problem is getting Fortran to specify a C++ type. I
thought that the import statement does that.
--
Dieter Britz
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