Re: Possible Bug: "** On entry to octave parameter number 13 had an illegal value"

[Jaroslav Hajek]

On Fri, Mar 27, 2009 at 5:02 PM, Andreas Romeyke <address@hidden> wrote:
> Hello,
>
> If I compile the head-version of Octave with ff. options
>
> CXXFLAGS="-pipe -O3 -march=native -ftree-loop-linear
> -fomit-frame-pointer -mfpmath=sse -mmmx -msse -msse2  -ffast-math"
>
> (and same FFLAGS) I got the message
>
> "** On entry to octave parameter number 13 had an illegal
> value\nSpeicherzugriffsfehler"
>
> by calling "./run-octave". If the flags are:
>
> "-pipe -O3 -march=native -funroll-loops"
>
> it works. After some compile runs I assume the problem is related to
> the  "-ffast-math".
>
> The problem is hard to debug, could anyone explain what the error
> message means in detail? If I grep for this message I got matches in:
>
> ./libcruft/STOP.patch:       $         ' had an illegal value' )
> ./libcruft/STOP.patch:       $         ' had an illegal value' )
> ./libcruft/lapack/*.f:*          < 0:  If INFO = -i, the i-th
> argument had an illegal value
>
>
> Do you have additional hints?
>
> Bye Andreas
>
>

This error is a side effect. Octave computes NaN at startup; this
error occurs if the test "octave_NaN == -1" that occurs in
src/octave.cc is somehow optimized so that it passes (or Octave_NaN
actually has the value -1).
Shortly stated, there is a number of parts of Octave that will not
work correctly with -ffast-math, in particular certain stuff in
lo-mappers, etc. In the future, it may be possible to allow specifying
such aggressive flags for certain pieces of code that are supposed to
be finite-only, but meanwhile, I suggest you just avoid -ffast-math
when compiling Octave.



-- 
RNDr. Jaroslav Hajek
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz