pb with oct file, return a matrix

[Alain Baeckeroot]

Hi

I wrote a DEFUN_DLD and have trouble to return a matrix, it segfault
at return retval or in main program M=boucle_cc(...)!
I tried to run in gdb (and mkoctfile -g) but it does not help me.

I think i have exactly copied a working DEFUN_DLD i have which 
returns a matrix, but ...

Any help/hint/url is welcome :-)
Alain

------------------------------------------------------
Here is the code (with printf for debugging)
DEFUN_DLD( boucle_cc, args, nargout, "usage : rMat = boucle_cc(..)\n") {
	int NDATA=10000;
	Matrix rMat(NDATA, 22);	// results
	octave_value_list retval;   // list of return values

	...compute and put everything in rMat...

		printf(" ici boucle_cc 7, avant retval(0)= rMat\n");
		printf(" rMat(0,0) = %lf, (9999,21) = %lf;\n", rMat(0,0), rMat(9999,21) );
	retval(0) = rMat;
		printf(" ici boucle_cc 8, avant return retval\n");
	return retval;
}
----------------------------------------------------
$ gdb /usr/usr/bin/octave
(gdb) r
octave 1> main
 ...
 ici boucle_cc 7, avant 'retval(0)= rMat;'
 rMat(0,0) = -0.018000, (9999,21) = 10.715615;
 ici boucle_cc 8, avant return retval
*** glibc detected *** /usr/bin/octave: free(): invalid next size (fast): 0x0b02f080 ***

Program received signal SIGSEGV, Segmentation fault.
---Type <return> to continue, or q <return> to quit---
[Switching to Thread 0xb59156c0 (LWP 27412)]
0xb7f3da90 in ?? () from /lib/ld-linux.so.2

   (gdb) c
Continuing.
panic: Segmentation fault -- stopping myself...
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F��xo�?qr\���?<ܣq���?{ ���?sɬ��
K3u at U�attempting to save variables to `octave-core'...��?�X��:▒�?:w�P�?�

Program received signal SIGSEGV, Segmentation fault.
0xb79774d0 in symbol_table::size () from /usr/lib/octave-3.0.1/liboctinterp.so
(gdb)  quit