Re: LOG(F) Error Model/Machine Differences

From n.holford@auckland.ac.nz Sun Aug 25 13:49:10 1996 Subject: Re: LOG(F) Error Model/Machine Differences > We have recently been working with analyses requiring error models > incorporating LOG(F). During this process, we discovered that this > type of $ERROR model is handled differently for a DEC Alpha machine > versus a SUN workstation. This note is a helpful observation about some of the subtle requirements for successful use of NONMEM. But it seems that the problem is incorrectly described as a machine difference when it would appear to be a difference in the compiler options used on the two machines. Can Luann or anyone else clarify if my interpretation is correct? And if so what compiler options control whether DIVIDE BY ZERO raises an error? Using the HP f77 compiler the +T option causes division by zero to raise an error while the default option returns +INF as the result (Note however that LOG(0) with HP f77 always returns -INF irrespective of the +T option!). If the DIVIDE BY ZERO error produced by LOG(0) and the DEC compiler can be trapped then an error handler can probably be added to the NONMEM code that returns -INF. This would only have to be done once instead of having to remember to use the work around Luann described in every NMTRAN control stream that uses the LOG(F) model. -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556 http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.html