This model illustrates a very simple external procedure call, along with the C source of the external function called from within the model. This function computes the average of a dense array, which corresponds to the contents of a two-dimensional identifier in the AIMMS model that is passed to it as an argument.
The C source code illustrates how the dense, linear, array must be interpreted as a two-dimensional data structure, given the number of elements for each dimension. It also illustrates how a function can be exported by the DLL in such a manner that AIMMS can find it runtime.
If the sizes of each dimension of a multi-dimensional identifier are rather large, you are strongly advised to pass the data in a sparse manner using the AIMMS API, rather than passing dense arrays. In such cases, data tends to be rather sparse (i.e. not many elements are non-default), and passing dense arrays would require an exuberant amount of memory.
External procedure, DLL.
A zip file with this example can be downloaded here.