Tech Tip: Mark 21 Fortran DLLs
Supported customers who take the NAG Fortran DLLs should have received a CD containing the Mark 21 version.
It is sensible to update, not only because of the new and improved routines, but because of the changes to the underlying software used. NAG use Intel's MKL to speed up computation using Basic Linear Algebra (BLAS) and LAPACK routines. Since we produced Mark 20 Intel have considerably improved upon the version of MKL that we used. In consequence the newer MKL that is used for Mark 21 is faster and more reliable.
You will also see some changes. We now provide two libraries. One uses MKL and one does not. The former is the one we would expect to be faster and is our recommendation; the latter uses high level NAG routines rather than the specialised MKL routines and is provided to allow the user to cross-check results if suspicions are aroused on some newer chip or hardware in the future.
We have made an organisational change too. At Mark 20 the library was split into two self-contained DLLs. The rationale was that one set comprised those routines that were, at a textual level, thread-safe and the other DLL was the complement of that set. If you had a thread-safe implementation of the DLLs this made sense, but the standard, and generally faster option, is the non-thread-safe DLL. The majority of our customers take this and were puzzled by the split. We have therefore combined the two DLLs, so that the whole library is now contained in one DLL.
Previous articles have described how the Mark 20 DLLs may be used from Excel. Mark 21 may of course be used from Excel in exactly the same manner. If you have Office 2007 and are struck by the clear presentational differences you might wonder whether Excel 2007 could use the NAG DLLs. It can indeed!
For specific technical advice in using NAG's products, please contact our technical experts.
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