[hts-users:01225] Re: LBFGS implementation for HTS2.1

["Alexander Gutkin" <alexander.gutkin@xxxxxxxxx>]

Hi Heiga,

   The problem you are experiencing with the g2c port on the 64bit
architecture is most likely due to the wrong byte alignment. If I am
not mistaken, there several places in the code where the control
parameters structure lb3_1 (accuracy etc.) is accessed through
dereferencing of lb3. That is not necessarily guaranteed to work.

           Regards,
                       Alexander.

On Thu, Mar 13, 2008 at 2:10 AM, Heiga ZEN (Byung Ha CHUN)
<zen@xxxxxxxxxxxxxxx> wrote:
> Hi,
>
>  Sacha Krstulovic wrote (2008/03/13 1:55):
>
>
>  > For the HTS2.1 release, is the LBFGS implementation going to remain
>  > written in Fortran, or will it be replaced by a C code implementation?
>
>  That LBFGS FORTRAN code originally comes from Jorge Nocedal, professor of Northwestern University.
>  I heard that it has been a public domain, so we can modify and redistribute it.
>  Actually I have one in C ported by g2c.
>  However, it has some problem on x86_64 environment, so I don't use it for now.
>
>
>  > In hts_engine from HTS-API 0.95, does the GV-related optimization
>  > correspond to the LBFGS algorithm, or is the C-code implementing
>  > a different optimization algorithm?
>
>  LBFGS is computationally more expensive than the steepest descent and quasi-Newton methods.
>  We design HMGenS for research and hts_engine API is for application.
>  Therefore, in hts_engine API, the quasi-Newton method (diagonal Hessian matrix) is used.
>  You can find the codes for this optimization at HTS_calc_derivative() and HTS_gv_parmgen() in lib/HTS_mlpg.c.
>
>  Regards,
>
>  Heiga ZEN (Byung Ha CHUN)
>
>  --
>  ------------------------------------------------
>   Heiga ZEN     (in Japanese pronunciation)
>   Byung Ha CHUN (in Korean pronunciation)
>
>   Department of Computer Science and Engineering
>   Nagoya Institute of Technology
>   Gokiso-cho, Showa-ku, Nagoya 466-8555 Japan
>
>   http://www.sp.nitech.ac.jp/~zen
>  ------------------------------------------------
>
>