Error Interacting with Commercial DLL about julia HOT 5 CLOSED

What's the API of the REFPROPdll function (is it really called like that?)? What are the types of hFld, hIn, hOut, iUnits, iMass, iFlag, a, b, z? Also, did you read https://docs.julialang.org/en/v1/manual/calling-c-and-fortran-code/ including all the caveats about Fortran?

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I don't know the dll, but generally Fortran expects arguments to be passed by reference. I.e. a pointer to the data. So Cint, Cdouble etc. might be inappropriate. I would try to specify the type as Ptr{Cint} and pass it as Ref(iUnits) etc. What it does about strings I do not know. It depends, I suspect.

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It looks like the main problem is the lack of necessary parameters.

Doc for REFPROPdll

https://refprop-docs.readthedocs.io/en/latest/DLL/high_level.html#f/_/REFPROPdll

#define RP_SIZE_T std::size_t
#define REFPROPdll_ARGS \
    char *,char *,char *,INT_REF,INT_REF,INT_REF,DOUBLE_REF,DOUBLE_REF,\
    double *,double *,char *,INT_REF,double *,double *,double *,DOUBLE_REF,INT_REF,char *,\
    RP_SIZE_T,RP_SIZE_T,RP_SIZE_T,RP_SIZE_T,RP_SIZE_T

https://github.com/CoolProp/REFPROP-headers/blob/2f206de280a71752e163e4fa6aff2ff358f464ac/REFPROP_lib.h#L438

There are some wrappers written in other languages for reference:
https://github.com/usnistgov/REFPROP-wrappers

from julia.

What's the API of the REFPROPdll function (is it really called like that?)? What are the types of hFld, hIn, hOut, iUnits, iMass, iFlag, a, b, z? Also, did you read https://docs.julialang.org/en/v1/manual/calling-c-and-fortran-code/ including all the caveats about Fortran?

The (Fortran) types of those parameters are char*, char*, char*, int, int, int, double, double, array(double)* respectively. I have read the docs, thanks for the link.

I don't know the dll, but generally Fortran expects arguments to be passed by reference. I.e. a pointer to the data. So Cint, Cdouble etc. might be inappropriate. I would try to specify the type as Ptr{Cint} and pass it as Ref(iUnits) etc. What it does about strings I do not know. It depends, I suspect.

Thanks for this advice, I messed around with parameter types and which to send as pointers and that got me past the error. I'm still having another error (read-only memory), but this was definitely an improvement.

It looks like the main problem is the lack of necessary parameters.

Doc for REFPROPdll

https://refprop-docs.readthedocs.io/en/latest/DLL/high_level.html#f/_/REFPROPdll

#define RP_SIZE_T std::size_t
#define REFPROPdll_ARGS \
    char *,char *,char *,INT_REF,INT_REF,INT_REF,DOUBLE_REF,DOUBLE_REF,\
    double *,double *,char *,INT_REF,double *,double *,double *,DOUBLE_REF,INT_REF,char *,\
    RP_SIZE_T,RP_SIZE_T,RP_SIZE_T,RP_SIZE_T,RP_SIZE_T

https://github.com/CoolProp/REFPROP-headers/blob/2f206de280a71752e163e4fa6aff2ff358f464ac/REFPROP_lib.h#L438

There are some wrappers written in other languages for reference: https://github.com/usnistgov/REFPROP-wrappers

I am confident I have the input parameters correct (except for type conversion), as I have worked with this DLL extensively in other languages. Most of those parameters you see in the #define result are outputs, not inputs.

Apologies for the screenshot, but here are the parameters defined in the documentation:

from julia.

As pointed out by @inkydragon, the ABI appears incorrect. This isn't really the kind of thing you can't just guess at. In particular different fortran compilers will sometimes implement ABIs differently, so the documention is not sufficient to determine the ABI. @inkydragon's reference to the C headers is likely your best bet for translation. Regardless, this is not a bug, so future discussion on this is best had at https://discourse.julialang.org/.

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