Excuse me all, I have failed to tell you that I am using both g77 and
Compaq Fortran, having had more success with the second, at least until
now.
Phillip Ezolt wrote:
>
> Jose,
> You really DON'T want to be using the GNU fortran compiler.
> Use the compaq fortran compiler at http://www.digital.com/fortran/linux/
>
> Cheers,
> --Phil
>
> Compaq: High Performance Server Division/Benchmark Performance Engineering
> ---------------- Alpha, The Fastest Processor on Earth --------------------
> Phillip.Ezolt@compaq.com |C|O|M|P|A|Q| ezolt@perf.zko.dec.com
> ------------------- See the results at www.spec.org -----------------------
>
> On Wed, 15 Dec 1999, [iso-8859-1] José Javier Zarate wrote:
>
> > Dear all
> >
> > I am not sure if this are the right lists so if you know better places
> > to ask please let me know. Excuse also the cross posting but I am
> > desperate.
> >
> > Not my english language skills neither my programming skills are very
> > good so please excuse my possible manifestations of ignorance.
> >
> > I am using a computer with EV56 microprocessor 633 MHz, API 164UX 2 MB
> > cache motherboard, 256 MB RAM and OS RedHat 6.0, kernel 2.2.5-16.
> >
> >
> > Well, the question is that I am trying to make run a pharmacokinetic
> > modelling program under Alpha/Linux.
> > The program comes as general Fortran code that you have to compile.
> >
> > Well, the first question is that since I installed
> > For setting up the program I should know some values referring to the
> > FPU characteristics. I will cite quoted from the installation manual:
> >
> >
> > "REPS Machine precision. The smallest floating point number
> > representable
> > in the machine such that when added to 1 the result sum is not 1.
> > TOL Machine tolerance. The smallest floating point number representable
> > in the machine divided by machine precision.
> > LARGE Machine infinity. This is the largest floating point number
> > representable in the machine.
> > EPS Mantissa lenght. This is the number 2**(-m), where m is the number
> > of binary digits occurring in the floating point mantissa.
> > SREPS Same as REPS but always single precision.
> > STOL Same as TOL but always single precision.
> > In single precision NONMEM, these six nunmbers are represented as
> > integer values in the integer variables IREPS, ITOL, LARGE, IEPS,
> > ISREPS, ISTOL.
> > In double precision NONMEM, double precision versions of REPS, TOL, and
> > LARGE are plced as pairs of integr values in two-dimensional integer
> > arrays IREPS, ITOL and LARGE. Single precision versions of EPS, ISREPS
> > and ISTOL.
> > The integer values in BLKDAT (a subroutine of the program) are made
> > equivalent via FORTRAN EQUIVALENCE statements to floating point
> > variables of the appropiate precisions."
> >
> > Double precision values are:
> > "
> > * IEEE CONSTANTS
> > *
> > C DATA IREPS,ITOL,LARGE,IEPS/1018167296,0,55574528,0,
> > C 1 2146435071,-1,864026624/
> > C DATA ISREPS,ISTOL/872415232,201326592/
> > *
> >
> > *
> > * INTEL CHIP CONSTANTS
> > *
> > DATA IREPS,ITOL,LARGE,IEPS/0,1018167296,0,55574528,
> > 1 -1,2146435071,864026624/
> > DATA ISREPS,ISTOL/872415232,201326592/
> > "
> >
> > Single precision values are:
> >
> > "
> > * IEEE CONSTANTS
> > *
> > C DATA IREPS,ITOL,LARGE,IEPS/872415232,201326592,
> > C 1 2139095039,864026624/
> > C DATA ISREPS,ISTOL/872415232,201326592/
> > *
> > "
> >
> > I have used Intel and IEEE values but this appears to cause errors
> > during
> > execution (in test runs I get floating point exceptions) unless I
> > compile without optimization. Intel values allow any kind of options
> > when compiling.
> > So, could any of you know those values for my microprocessor or where to
> > find them? I will try to give you more information as soon as I can find
> > it.
> >
> >
> > When comparing the time it needs for some problems with the same time
> > from a PIII 450 MHz it simply trounces the Alpha in some kind of
> > problems (by a factor of two), while resolving some other problems
> > result in the Alpha outperforming the PIII by a factor or two. I am
> > really lost.
> > Are there any benckmarking utilities available that allow me to check if
> > the machine is running properly? Or any simple way to check if
> > everything is working properly?
> > Could any of you have some Fortran program that I could compile and
> > check the time it needs to execute?
> > Are there any mods I could perform to improve the computer performance?
> >
> >
> > As someone appears to be using the same compilers as I do, would it be
> > possible to know what the program is doing (wich subroutines it is using
> > during a givwen run an d how much time is it taking). Back to my times
> > of BASIC (sorry) and Pascal you could do it and see wich lines of code
> > were being executed. Being a program used for clinical purposes I cannot
> > modify the source code without previous agreement of the makes but I
> > think that I could apply different optimizations to different
> > subroutines, as I have seen that applying different optimization levels
> > to the whole lot appear to change favourably the performance on some
> > problems and degrade it on some others. Any clues would be very welcome.
> >
> >
> > When installing the program I have also the choice of using single or
> > double precision installation.
> > Quoting again:
> > "Some scientific workstations are described as having "64 bit
> > architecture". This tipically describes the width of the data bus, not
> > the size of the floating point word, wich is 32 bits. Double precison is
> > recommended for such machines."
> >
> > Supposing that the ability of having 64 bit long word allows the
> > microprocessor to work with longer than standard single precision
> > values so that I could install Single precision version without losing
> > quality in the results and improving speed. Or, if someone knows enough
> > about the architecture of the processor and how to do it, I could try to
> > do what Intel Pentium (and next) do, perform various tasks in parallel.
> > Any of those tricks would be very useful. If somebody knows how to
> > convince the compiler for having such behaviour I would be very grateful
> > if he or sehe could share his knowledge.
> >
> >
> > I have tried to overclock from 633 to 667 but since I did I get
> > f77: Internal compiler error: program f771 got fatal signal 11
> > when compiling large sets of *.f files.
> > After getting back to 633 everything seems to be normal again.
> > Any clues about overclocking? I thoght that 5% overclocking wasn't shuch
> > a big deal.
> >
> >
> > Finally, floating point exception handling.
> > Ther are various ways to do this in different architectures and OSs, I
> > need that the program terminates in case of FP exception unless is
> > underflow where is considered safe to set the value to zero. Under
> > Compaq fortran compiler it appears to be done by the option fpe at
> > different levels but I am not sure neither know what is gradual
> > underflow (something proposed in the online manual as an alternative to
> > setting the number to zero).
> >
> >
> > Thanks all and happy Christmas
> >
> > --
> > JJ Zarate
> > Departamento de Farmacia y Tecnologia Farmaceutica
> > http://www.unav.es/farmacia/dptos/farmytec/index.htm
> >
> > --
> > To unsubscribe: send e-mail to axp-list-request@redhat.com with
> > 'unsubscribe' as the subject. Do not send it to axp-list@redhat.com
> >
> >
-- JJ Zarate Departamento de Farmacia y Tecnologia Farmaceutica http://www.unav.es/farmacia/dptos/farmytec/index.htm
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