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From: James Tursa on 18 Jun 2008 18:33
"Richie Cotton" <richierocks(a)nospam.gmail.com> wrote in
message <g3bd6u$cb8$1(a)fred.mathworks.com>...
> I'm trying to understand how Mex files work, and I'm
working
> my way through the built-in examples. Most work fine,
but
> the 'dynamically allocating memory' example throws an
error.
>
> In this example, the gateway routine and the
computational
> subroutine are in two separate files. I presume this is
> valid practise, but the compiler throws an 'unresolved
> external symbol' error when linking.
>
> The example files are in
matlabroot\extern\examples\refbook,
> named dblmat.f and compute.f
>
> Both files compile fine, but running mex dblmat.f
results in
> the output:
> Creating library
> C:\DOCUME~1\rcotton\LOCALS~1\Temp\mex_98A65341-3E5D-4E6E-
8085-421F61D78F59\templib.lib
> and object
> C:\DOCUME~1\rcotton\LOCALS~1\Temp\mex_98A65341-3E5D-4E6E-
8085-421F61D78F59\templib.exp
>
> dblmat.obj : error LNK2001: unresolved external symbol
> _COMPUTE(a)12
> dblmat.mexw32 : fatal error LNK1120: 1 unresolved
externals
>
> I'm using v2007b, with Compaq Visual Fortran 6.6 under
Win XP.
>
> How do I persuade Matlab/Visual Fortran to recognise the
> computational subroutine?

From what you have written, it looks like you are doing
this:

mex dblmat.f

when you should be doing this:

mex dblmat.f compute.f

i.e., you need to give the mex command all of the pieces.
This would also be the case if, for example, compute.f was
some other pre-compiled object code or library etc. For
example, if your mex routine needed a Fortran source code
file and a pre-compiled object code and a library dll the
mex command would look like this:

mex mysource.f myobj.obj mylib.dll

James Tursa

From: Richie Cotton on 19 Jun 2008 05:17
> From what you have written, it looks like you are doing
> this:
>
> mex dblmat.f
>
> when you should be doing this:
>
> mex dblmat.f compute.f

Thanks. With hindsight, that's embarrassingly obvious.
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