From help-octave-request at bevo dot che dot wisc dot edu Thu Feb 14 13:18:19 2002
Subject: Re: Loading files from within c++ (feval)
From: Paul Kienzle <pkienzle at jazz dot ncnr dot nist dot gov>
To: Douglas Eck <doug at idsia dot ch>, help-octave@bevo.che.wisc.edu
Date: Thu, 14 Feb 2002 14:15:37 -0500

Not having looked at the relevant code, I'm guessing that load is
attempting to create a variable in the current symbol table but
failing because you haven't initialized the current symbol table.
Maybe something like:
	octave_value a;
	curr_sym_tab = new symbol_table(10);
	... your feval stuff ...
	symbol_record *sr = curr_sym_tab->lookup("a");
	if (sr && sr->is_defined ()) a = sr->def ();
	     
Paul Kienzle
pkienzle at users dot sf dot net
 
On Thu, Feb 14, 2002 at 02:28:04PM +0100, Douglas Eck wrote:
> I'm reluctant to file a bug report but I can't get feval to
> work in 2.1.35 in a stand-alone C++ application. What I want
> to do is load a .mat file. That .mat file contains
> matrices and structs.  Is this even possible?
> I've tried many permutaitons of this feval call
> using the mailing list archives as a guide. None seem
> to work. Here's one failed attempt. :
> 
> #include <octave/oct.h>
> #include <octave/ov-struct.h>
> #include <octave/parse.h>
> #include <octave/oct-map.h>
> #include <math.h>
> int main(int argc, char * argv[]) {
>    octave_value_list args;
>    args(0) = "tst.mat";
>    args(1) = "a";
>    feval("load", args, 0); // no arguments returned
>    cout << "done" << endl;
> 
> I took that from Paul K's posting of a while back. I compiled it using;
> 
> g++ -pg -g tstFile.o  -o tstFile -L/usr/lib/octave-2.1.35 -L/usr/src/octave-2.1.35/kpathsea \
>     -lblas -loctave -loctinterp -ldl  -lcruft  -lg2c -ltermcap -lhdf5 -lreadline -lkpathsea -lfftw
> 
> And I get a segfault. This happens when I run on our alpha or on my pentium box.
> Both run Dirk's debian packages.
> 
> Here's the segfault message from GNU gdb 5.1
> (gdb) run
> Starting program: /home/doug/src/tstFile/tstFile
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x200009aee38 in symbol_table::hash () from /usr/lib/octave-2.1.35/liboctinterp.so.2.1.35
> 
> Cheers,
> Doug
> 
> 
> 
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Octave is freely available under the terms of the GNU GPL.

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