From owner-bug-octave at bevo dot che dot wisc dot edu  Sun Dec  8 19:29:35 1996
Subject: Matherr behavior
From: Joao Cardoso <jcard at merlin dot inescn dot pt>
To: bug-octave at bevo dot che dot wisc dot edu
Date: Sun, 8 Dec 96 22:26:42 GMT



Hi,

'matherr' is set up to don't print warning messages. Is this wise? 
With singularity, domain or other errors the user would be warned 
of possible errors, and would not blindy thrust the results. After 
all, I remember seeing in matlab errors about the condition number 
of matrices.

This subject arose because of 222^222 != Inf. I also suffer from
this behaviour, so I made matherror return 0 in sysdeps.cc:

   octave:1> 222^130
   ans =  1.0614e+305
   octave:2> 222^140
   ans =  3.4028e+38
   octave:3> log(0)
   log: SING error
   ans =  -3.4028e+38

My libm returns +/-MAXFLOATS instead of +/-HUGE_VAL, and matherror 
is not called. Is this standard, or is just SCO? The man page
states that matherr is conformant with:

    AT&T SVID Issue 2, but has been withdrawn from XPG3.

octave-1.94 configure run OK with me--it added -mieee-fp to both 
CFLAGS and CXXFLAGS, what I think(!) is correct and I was not aware 
of.

Thanks,
Joao

--
Joao Cardoso, INESC  |  e-mail: jcardoso at inescn dot pt
R. Jose Falcao 110   |  tel:    + 351 2 2094345
4000 Porto, Portugal |  fax:    + 351 2 2008487