Tech Tip: Advice for Upgrading to new versions of the NAG Libraries

When new versions of any of the NAG Libraries become available, it is appropriate to give some general advice.

Firstly, we recommend sites to upgrade to the new Mark whenever possible. This is because a new Mark of the Library often includes algorithm improvements and incorporates known bug fixes. An obvious further incentive to upgrade is of course the new routines.

NAG never withdraws a routine without adequate notice. In general at least two Marks notice is given of our intention to withdraw a routine. We announce our intentions by placing an asterisk beside the routine name in the relevant chapter contents document. On receipt of a new Library it therefore makes sense to check on the status of routines that you expect to be using over a prolonged period of time.

If one of your favourite routines is marked for withdrawal it will have a replacement that we feel is better, so our recommendation is to adapt your program to call this newer routine if at all possible. To help you do this, a document entitled "Advice on Replacement Calls for Withdrawn/Superseded Routines" is available at the front of the manual, in the introductory materials.

If you decide not to do this, then please remember to save the associated documentation for the routine in question. You would be surprised how useful this may be in several years time. An executable compiled and linked with a static library implementation of the NAG Library will continue to work indefinitely. Your problems will only really begin if you subsequently decide to change your program and have not kept the original NAG Library. Shareable libraries are another matter. Because the NAG Library code is not tightly bound into your executables you will need the original library around at all times, if the routine you are calling is no longer in the current library.

For specific technical advice in using NAG's products, please contact our technical experts.

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