From octave-sources-request at bevo dot che dot wisc dot edu  Fri Oct  1 06:00:56 1999
Subject: Problem with vector classes
From: Thomas Walter <walter at pctc dot chemie dot uni-erlangen dot de>
To: octave-sources at bevo dot che dot wisc dot edu
Date: Fri, 1 Oct 1999 13:00:36 +0200


Hello,
I have a problem with the behaviout of 'ColumnVector', 'RowVector' and
the direct access to their data using 'fortran_vec()'.

Example code:

  const ColumnVector xv = args (0).vector_value();
  const double *my_data = xv.fortran_vec();

Using 'gcc-2.95.1' on a linux-box gives the following error message:

heap_sort.cc: In function `class octave_value_list Frank_data(const octave_value_list &, int)':
heap_sort.cc:321: passing `const ColumnVector' as `this' argument of
`double * Array<double>::fortran_vec()' discards qualifiers


current fix to the example:

  /* const */ ColumnVector xv = args (0).vector_value();
  const double *my_data = xv.fortran_vec();


Is it possible or are there plans to fix this?

This could improve the coding to C-style functions which want a
pointer to the data but for read only.

Thanks for any hint

Bye
Thomas


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----------------------------------------------
Dipl. Phys. Thomas Walter
Inst. f. Physiklische Chemie II
Egerlandstr. 3				Tel.: ++9131-85 27326 / 27330
91058 Erlangen, Germany			email: walter at pctc dot chemie dot uni-erlangen dot de