[MBDyn-users] contribution in MBDYN

Louis Gagnon louis.gagnon at polimi.it
Thu Mar 16 09:45:41 CET 2017

Hi Shaunak and welcome to the MBDyn list,

Your interest in mathematically intense projects is very interesting to us.

As noted by Andrea and Janga, do keep in mind the entry test as it has 
the most weight for proposal evaluation and also gets you familiar with 
the code.

I have limited knowledge concerning the AD project, but I think the use 
of elementary functions may be limited, for example in the wheel2 module 
mentioned in the document prof. Mantegazza sent you, by the fact that 
sometimes the functions are not analytically differentiable. I'm 
thinking of wheel modules because they can take road longitudinal 
profile data which consist of tabular data and have no analytic version.

Best Regards,


On 16-Mar-2017 06:49 AM, Shaunak Dixit wrote:
> I have gone through the document of automatic differentiation since 
> the problem in using the following idea is that in run-time ADT 
> capabilities are slower than the corresponding elements with 
> hand-coded Jacobian matrices.
> I would like to know if we implement the idea of elementary functions.
>  After converting the function *_F_* into elementary functions.
> Then elementary functions can be derived and if _*Pi,j*_  is the 
> derivative of *_Pi_*, with respect to _*xi*_ The derivative of _*F*_ 
> with respect to _*Xk*_ is then obtained by adding all the products 
> *_ Pi,j_* between *_Xk_* and *_Xn_*.
> where Xk and Xn are the different variables.
> with the following method, approximately 25% to 30% of the total CPU 
> time can be saved.
> thanks
> On Thu, Mar 16, 2017 at 5:11 AM, Paolo Mantegazza 
> <paolo.mantegazza at polimi.it <mailto:paolo.mantegazza at polimi.it>> wrote:
>     In relation to automatic differentiation have a look at:
>     https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwjs48mb19nSAhXBiRoKHRHaANIQFggzMAE&url=https%3A%2F%2Fhome.aero.polimi.it%2Fantasme%2FAutodiffImplementation.pdf&usg=AFQjCNEWzkkbqRDCLgeT-rwedB8nA_uOgw
>     <https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwjs48mb19nSAhXBiRoKHRHaANIQFggzMAE&url=https%3A%2F%2Fhome.aero.polimi.it%2Fantasme%2FAutodiffImplementation.pdf&usg=AFQjCNEWzkkbqRDCLgeT-rwedB8nA_uOgw>
>     P. Mantegazza.
>     ________________________________________
>     From: MBDyn-users [mbdyn-users-bounces at mbdyn.org
>     <mailto:mbdyn-users-bounces at mbdyn.org>] on behalf of Janga Reddy
>     [janga1997 at gmail.com <mailto:janga1997 at gmail.com>]
>     Sent: Wednesday, March 15, 2017 8:30 PM
>     To: Shaunak Dixit
>     Cc: mbdyn-users at mbdyn.org <mailto:mbdyn-users at mbdyn.org>
>     Subject: Re: [MBDyn-users] contribution in MBDYN
>     Hi Shaunak,
>     Have you checked out the entry tests requirements for the projects
>     you like?
>     https://louisgag.github.io/mbdyn-gsoc-projects/#/entry_test
>     <https://louisgag.github.io/mbdyn-gsoc-projects/#/entry_test>
>     Completing the common entry tests (or project specific entry
>     tests), is the first step before proceeding further.
>     Regards,
>     VSN Reddy Janga
>     On Wed, Mar 15, 2017 at 10:54 PM, Shaunak Dixit
>     <sdixit_be15 at thapar.edu
>     <mailto:sdixit_be15 at thapar.edu><mailto:sdixit_be15 at thapar.edu
>     <mailto:sdixit_be15 at thapar.edu>>> wrote:
>     I want to contribute in MBDYN. Currently, I'm doing software
>     engineering and I have made many projects on c++.
>     so I would like to work on any of the project related to c++ and
>     some mathematics portion
>     1- Convergence Criteria
>     2- Embedded Optimization
>     3- Automatic Differentiation
>     I think I can perform well on these projects so please help me a
>     little bit and
>     Please provide me some guidance on how to start contributing to
>     the project.
>     Thank You
>     Shaunak
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Louis Gagnon, Ph.D.
Postdoctoral fellow
Dipartimento di Scienze e Tecnologie Aerospaziali
Politecnico di Milano
+39 02 2399 8642

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