And Jaroslav Hajek writes: > I'm not sure I understand you well (I don't know anywhere as much as > you about the IEEE fp), but are you saying that with certain hardware > and software support, it is possible to check whether NaNs occured > *without* inserting software checks into every operation?
Yes. The main problem is scoping the checks appropriately. An external library might generate NaNs and handle them internally but not clear the invalid flag. LAPACK's MRRR eigenvalue solvers do this, alas. The push-back against using modern Fortran in LAPACK is *huge*, so don't bet on our isolating the exceptional flags via F03's support any time soon. > If yes, I think it would be nice to have that in Octave, even if it > would work only on some systems and require configure testing. Access via C99's fetestexcept (FE_INVALID) is documented well in GNU libc's manual: http://www.gnu.org/software/libc/manual/html_node/Status-bit-operations.html And at some point, Octave also should set its operating mode when used as a library: http://www.gnu.org/software/libc/manual/html_node/Control-Functions.html These also can help isolate exceptional conditions when calling external code, but that's deep surgery. These all involve more mucking with the build system, testing across many platforms, etc. So post-3.2, and the implementation trade-offs might be worth a short paper in TOMS. Jason ------------------------------------------------------------------------------ Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are powering Web 2.0 with engaging, cross-platform capabilities. Quickly and easily build your RIAs with Flex Builder, the Eclipse(TM)based development software that enables intelligent coding and step-through debugging. Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com _______________________________________________ Octave-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/octave-dev
