From help-request at octave dot org Tue Jul 12 08:07:16 2005
Subject: Re: basic DLD help?
From: =?ISO-8859-1?Q?S=F8ren_Hauberg?= <soren at hauberg dot org>
To: Shai Ayal <shaia at biocontrol dot co dot il>
CC: help at octave dot org
Date: Tue, 12 Jul 2005 15:06:32 +0200

Hi,
You need to return something. If you need to return the number 7, do this:

return octave_value(7);

If you need to return several values do:

octave_value_list ret;
ret.append(value1);
ret.append(value2);
// on so on...
return ret;

If you don't want to return anything at all, do:

return octave_value();

The last one is easy to forget.It would be nice if the compiler was able 
to catch  this, but apperently it can't.

/Søren

Shai Ayal wrote:
> Hi all,
> 
> I am probably missing something basic here, but why does this not work?
> 
> [bash] > cat > test.cc
> #include "oct.h"
> 
> DEFUN_DLD (test, args, ,"")
> {
> 
>   double* y = args(0).vector_value().fortran_vec();
> 
>   octave_stdout << ">> " << y[0] << "," << y[1] << "\n";
> 
> 
> }
> EOF
> 
> [bash] > mkoctfile -v test.cc
> g++ -c -fPIC -I/usr/local/include/octave-2.1.71 
> -I/usr/local/include/octave-2.1.71/octave -I/usr/local/include -mieee-fp 
> -g -O2 test.cc -o test.o
> g++ -shared -Wl,-Bsymbolic -o test.oct test.o 
> -L/usr/local/lib/octave-2.1.71 -loctinterp -loctave -lcruft -lcblas 
> -lf77blas -latlas -lfftw3 -lreadline -lncurses -ldl -lm 
> -L/usr/lib/gcc-lib/i386-redhat-linux/3.3.2 
> -L/usr/lib/gcc-lib/i386-redhat-linux/3.3.2/../../.. -lfrtbegin -lg2c -lm 
> -lgcc_s
> 
> 
> [bash] > octave
> GNU Octave, version 2.1.71 (i686-pc-linux-gnu).
> Copyright (C) 2005 John W. Eaton.
> This is free software; see the source code for copying conditions.
> There is ABSOLUTELY NO WARRANTY; not even for MERCHANTIBILITY or
> FITNESS FOR A PARTICULAR PURPOSE.  For details, type `warranty'.
> 
> Additional information about Octave is available at http://www.octave.org.
> 
> Please contribute if you find this software useful.
> For more information, visit http://www.octave.org/help-wanted.html
> 
> Report bugs to <bug at octave dot org> (but first, please read
> http://www.octave.org/bugs.html to learn how to write a helpful report).
> 
> octave:1> a=[1,2,3];
> octave:2> test(a)
> panic: Segmentation fault -- stopping myself...
>  >> 1,2
> attempting to save variables to `octave-core'...
> save to `octave-core' complete
> Segmentation fault
> 
> 
> 
> 
> -------------------------------------------------------------
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> 
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Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
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