Re: log2 replacement

[Jaroslav Hajek]

On Tue, Apr 29, 2008 at 8:40 PM, Jaroslav Hajek <address@hidden> wrote:
>
> On Tue, Apr 29, 2008 at 8:19 PM, John W. Eaton <address@hidden> wrote:
>  > On 25-Apr-2008, Jaroslav Hajek wrote:
>  >
>  >  | hello,
>  >  |
>  >  | please consider the attached changeset.
>  >  | The current log2 behaviour with two outputs (`[f, e] = log2(x)') is
>  >  | inconsistent with Matlab in a number of cases, (x = Inf, x = NaN) or
>  >  | just plain wrong (x = realmax). Also, on most of the systems the
>  >  | 2-output version can be mapped directly to frexp (a C89 function),
>  >  | which is probably what Matlab also does. I have implemented the
>  >  | single-output log2 as a mapper for octave_value (aka log, log10 etc),
>  >  | and the two-output version as an overload in liboctave/lo-mappers.cc
>  >  | with a replacement if frexp is not detected. The DEFUN is in
>  >  | DLD-FUNCTIONS rather than mappers.cc directly, because it is not a
>  >  | simple mapper and thus did not seem to fit "aesthetically" to
>  >  | mappers.cc (but that can be easily changed).
>  >  |
>  >  | Note that the 2-output version is also extended beyond matlab
>  >  | behaviour for complex input - while matlab ignores the imaginary part
>  >  | (with a warning), this new version gives the result with f complex,
>  >  | satisfying 1/2 <= abs(f) < 1, e integer - because it makes good sense
>  >  | also for complex numbers.
>  >
>  >  With this patch, I see the following error with make check:
>  >
>  >   src/DLD-FUNCTIONS/hex2num.cc ........................... PASS    2/2
>  >   src/DLD-FUNCTIONS/log2.cc .............................. PASS    0/2    
> FAIL 2
>  >   src/DLD-FUNCTIONS/lookup.cc ............................ PASS   16/16
>  >   src/DLD-FUNCTIONS/lsode.cc ............................. PASS    5/5
>  >   src/DLD-FUNCTIONS/luinc.cc ............................. PASS    2/2
>  >   src/DLD-FUNCTIONS/matrix_type.cc ....................... PASS   51/51
>  >   src/DLD-FUNCTIONS/max.cc ............................... PASS   12/12
>  >   src/DLD-FUNCTIONS/qr.cc ................................ PASS   21/21
>  >   src/DLD-FUNCTIONS/quad.cc .............................. PASS    6/6
>  >   src/DLD-FUNCTIONS/rand.cc .............................. PASS   57/57
>  >   src/DLD-FUNCTIONS/regexp.cc ............................ PASS   81/81
>  >   src/DLD-FUNCTIONS/time.cc .............................. PASS   13/13
>  >   src/DLD-FUNCTIONS/tsearch.cc ........................... PASS    6/6
>  >   src/data.cc ............................................ PASS   98/98
>  >   src/mappers.cc ......................................... PASS    7/7
>  >   src/ov-fcn-handle.cc ...................................panic: 
> Segmentation fault -- stopping myself...
>  >  make[2]: *** [check] Segmentation fault
>  >  make[2]: Leaving directory `/scratch/jwe/build/octave-tmp/test'
>  >  make[1]: *** [check] Error 2
>  >  make[1]: Leaving directory `/scratch/jwe/build/octave-tmp'
>  >  make: *** [check] Error 2
>  >
>  >  Does it work properly for you?
>  >
>  >  jwe
>  >
>
>  Umm, I think it did. I'll check again against the newest sources.
>
>
>
>  --
>  RNDr. Jaroslav Hajek
>  computing expert
>  Aeronautical Research and Test Institute (VZLU)
>  Prague, Czech Republic
>  url: www.highegg.matfyz.cz
>

OK, now I get the failure as well. Further I discovered a typo
(triggered only when HAVE_FREXP is undefined). I'll investigate this
and resubmit eventually.

regards,

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