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From: Rafael Vazquez <vazquez@im...>  20120221 18:04:41

Il 21/02/2012 14:43, c. ha scritto: > On 21 Feb 2012, at 15:00, cyril cassisa wrote: > > > >> *Do you think that I am going on a big complex mess ? or do you think it >> will be only simple modifications ?* >> > I think it shouldn't be a big problem if you just skip all the tensorproduct based classes and their > specific methods (those with neame ending in _tp). > > Yes, I agree that it is better to start without the _tp functions. Maybe in a second step you can use some of the ideas there, but I don't recommend to use them for now. Rafa 
From: Rafael Vazquez <vazquez@im...>  20120221 17:57:08

Dear Cyril, from your explanation I understand that you have defined the structure, but not the functions to work with it. The most important thing is to write the functions to evaluate the basis functions (and derivatives) at some points, and to evaluate the parametrization (and derivatives) of your domain. Kind of a RCKBS toolbox. Once you have this toolbox, computing the space shouldn't give you any trouble. And as you said, you also have to change the quadrature rule. For this you must decide which are the quadrature points in the curved elements of the parametric domain, and give a function to compute them, but the fields of the msh structure should remain basically the same. Regards, Rafa Il 21/02/2012 10:30, cyril cassisa ha scritto: > Hi everyone, > > I am working on other BSpline functions called Regular CurvedKnot > BSpline (RCKBS). > These functions are interesting for representing particular geometries > (surfaces and volumes) for example it can deal with continuity variation > over the domain. > The parametric domain is then not a regular grid as for BSpline and Nurbs. > > I am trying to incorporate RCKBS in GeoPDEs toolbox. But I encounter some > difficulties. > For that I create a new structure RCKBS using the same style as NURBS > structure. > Then I see that I also have to modify the mesh stucture. > Because in the case of RCKBS, the knot vector varies over the parametric > domain. For example for a surface: >  Uknot(v): Uknot is function of the v direction >  Vknot(u): Vknot is function of the u direction > Then I have a lowerbound and upperbound knot vectors for U and for V. > > I think that then, I will have to modify the quadratic rule computation as > my parametric domain is not regular on u and v direction, modify the msh > and space as well. > *Do you think that I am going on a big complex mess ? or do you think it > will be only simple modifications ?* > > I have also another question about the GeoPDEs toolbox. > For surfaces you consider that we are necessarily in 2D and volume is for > 3D. > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical > points are in 3d space but knots are only on U and V directions ?* > I try to consider my 3D surface as a volume with no depth but I got some > bugs then from boundary condition problem (I think). > > Thank you very much for your help. > Thanks to GeoPDEs developpers. It is very nice to have access to an open > source IGA toolbox. > Hope I will be able to bring my contribution on it. > > Sincerely > > Cyril Cassisa. > PostDoc INRIA > 
From: Rafael Vazquez <vazquez@im...>  20120221 17:37:32

Dear all, Il 21/02/2012 14:58, Dede' Luca ha scritto: > Dear all, > > >> > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical >> > points are in 3d space but knots are only on U and V directions ?* >> >> just because no one never implemented it, I don't see why it should not work to derive a class for spaces, >> actually I think it has already been done by someone at EPFL >> > Yes, a student did an attempt for a scalar PDE defined on a surface. It is relatively easy to implement it by using the existing functions as a starting point. We did not submit our contribution because the implementation was very much 'ad hoc'. > > In fact, a couple of people asked me the same thing before, and I think this could be an interesting contribution. Luca, it would be great if you (or your student) could find the time to prepare the simplest example. Regards, Rafa 
From: c. <carlo.defalco@gm...>  20120221 16:13:07

On 21 Feb 2012, at 20:57, cyril cassisa wrote: > I will skip the tensorproduct based classes and their specific methods but I will have to modify all function related to knots vectors. Yes, the nurbs toolbox is really quite specific for nurbs and bsplines so there is quite a few functions you will have to replace there. For an example of using different knot vectors for different functions you might want to have a look at the function tbasisfun: http://octave.svn.sourceforge.net/viewvc/octave/trunk/octaveforge/extra/nurbs/inst/tbasisfun.m?view=log c. 
From: cyril cassisa <ccassisa@gm...>  20120221 15:27:29

Thanks for your fast answers. For the surface in 3D, I see that it is quite easy to change the actual toolbox. Thanks for the advices for the modification I have to make for the geometric function. I will skip the tensorproduct based classes and their specific methods but I will have to modify all function related to knots vectors. I will inform you later about the advancement of my work. Sincerely Cyril Cassisa On Tue, Feb 21, 2012 at 9:58 PM, Dede' Luca <luca.dede@...> wrote: > Dear all, > > > > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the > physical > > > points are in 3d space but knots are only on U and V directions ?* > > > > just because no one never implemented it, I don't see why it should > not work to derive a class for spaces, > > actually I think it has already been done by someone at EPFL > > Yes, a student did an attempt for a scalar PDE defined on a surface. It is > relatively easy to implement it by using the existing functions as a > starting point. We did not submit our contribution because the > implementation was very much 'ad hoc'. > > Best regards, > > Luca Dede' > > > >  > Luca DEDE', Dott.Ing., PhD > > Researcher, Lecturer EDMA > CMCS  Chair of Modeling and Scientific Computing > MATHICSE  Mathematics Institute of Computational Science and Engineering > EPFL  Ecole Polytechnique Federale de Lausanne > > Office: MA C2 557, Av. Piccard, Station 8, CH1015 Lausanne, Switzerland > Phone: +41 21 693 0318 > Fax: +41 21 693 5510 > Email: luca.dede@... > Web: http://sma.epfl.ch/~dede/ > >  > > ________________________________________ > From: c. [carlo.defalco@...] > Sent: Tuesday, February 21, 2012 2:43 PM > To: cyril cassisa > Cc: Geopdesusers@... > Subject: Re: [Geopdesusers] Replacing Nurbs with CurvedKnot BSpline in > GeoPDEs > > On 21 Feb 2012, at 15:00, cyril cassisa wrote: > > > > *Do you think that I am going on a big complex mess ? or do you think it > > will be only simple modifications ?* > > I think it shouldn't be a big problem if you just skip all the > tensorproduct based classes and their > specific methods (those with neame ending in _tp). > > > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical > > points are in 3d space but knots are only on U and V directions ?* > > just because no one never implemented it, I don't see why it should not > work to derive a class for spaces, > actually I think it has already been done by someone at EPFL > > > Thank you very much for your help. > > Thanks to GeoPDEs developpers. It is very nice to have access to an open > > source IGA toolbox. > > Hope I will be able to bring my contribution on it. > > > > Sincerely > > > > Cyril Cassisa. > > PostDoc INRIA > > > > >  > Keep Your Developer Skills Current with LearnDevNow! > The most comprehensive online learning library for Microsoft developers > is just $99.99! Visual Studio, SharePoint, SQL  plus HTML5, CSS3, MVC3, > Metro Style Apps, more. Free future releases when you subscribe now! > http://p.sf.net/sfu/learndevnowd2d > _______________________________________________ > Geopdesusers mailing list > Geopdesusers@... > https://lists.sourceforge.net/lists/listinfo/geopdesusers > 
From: Dede' Luca <luca.dede@ep...>  20120221 13:59:09

Dear all, > > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical > > points are in 3d space but knots are only on U and V directions ?* > > just because no one never implemented it, I don't see why it should not work to derive a class for spaces, > actually I think it has already been done by someone at EPFL Yes, a student did an attempt for a scalar PDE defined on a surface. It is relatively easy to implement it by using the existing functions as a starting point. We did not submit our contribution because the implementation was very much 'ad hoc'. Best regards, Luca Dede'  Luca DEDE', Dott.Ing., PhD Researcher, Lecturer EDMA CMCS  Chair of Modeling and Scientific Computing MATHICSE  Mathematics Institute of Computational Science and Engineering EPFL  Ecole Polytechnique Federale de Lausanne Office: MA C2 557, Av. Piccard, Station 8, CH1015 Lausanne, Switzerland Phone: +41 21 693 0318 Fax: +41 21 693 5510 Email: luca.dede@... Web: http://sma.epfl.ch/~dede/  ________________________________________ From: c. [carlo.defalco@...] Sent: Tuesday, February 21, 2012 2:43 PM To: cyril cassisa Cc: Geopdesusers@... Subject: Re: [Geopdesusers] Replacing Nurbs with CurvedKnot BSpline in GeoPDEs On 21 Feb 2012, at 15:00, cyril cassisa wrote: > *Do you think that I am going on a big complex mess ? or do you think it > will be only simple modifications ?* I think it shouldn't be a big problem if you just skip all the tensorproduct based classes and their specific methods (those with neame ending in _tp). > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical > points are in 3d space but knots are only on U and V directions ?* just because no one never implemented it, I don't see why it should not work to derive a class for spaces, actually I think it has already been done by someone at EPFL > Thank you very much for your help. > Thanks to GeoPDEs developpers. It is very nice to have access to an open > source IGA toolbox. > Hope I will be able to bring my contribution on it. > > Sincerely > > Cyril Cassisa. > PostDoc INRIA  Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL  plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnowd2d _______________________________________________ Geopdesusers mailing list Geopdesusers@... https://lists.sourceforge.net/lists/listinfo/geopdesusers 
From: c. <carlo.defalco@gm...>  20120221 13:44:17

On 21 Feb 2012, at 15:00, cyril cassisa wrote: > *Do you think that I am going on a big complex mess ? or do you think it > will be only simple modifications ?* I think it shouldn't be a big problem if you just skip all the tensorproduct based classes and their specific methods (those with neame ending in _tp). > *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical > points are in 3d space but knots are only on U and V directions ?* just because no one never implemented it, I don't see why it should not work to derive a class for spaces, actually I think it has already been done by someone at EPFL > Thank you very much for your help. > Thanks to GeoPDEs developpers. It is very nice to have access to an open > source IGA toolbox. > Hope I will be able to bring my contribution on it. > > Sincerely > > Cyril Cassisa. > PostDoc INRIA 
From: cyril cassisa <ccassisa@gm...>  20120221 09:31:08

Hi everyone, I am working on other BSpline functions called Regular CurvedKnot BSpline (RCKBS). These functions are interesting for representing particular geometries (surfaces and volumes) for example it can deal with continuity variation over the domain. The parametric domain is then not a regular grid as for BSpline and Nurbs. I am trying to incorporate RCKBS in GeoPDEs toolbox. But I encounter some difficulties. For that I create a new structure RCKBS using the same style as NURBS structure. Then I see that I also have to modify the mesh stucture. Because in the case of RCKBS, the knot vector varies over the parametric domain. For example for a surface:  Uknot(v): Uknot is function of the v direction  Vknot(u): Vknot is function of the u direction Then I have a lowerbound and upperbound knot vectors for U and for V. I think that then, I will have to modify the quadratic rule computation as my parametric domain is not regular on u and v direction, modify the msh and space as well. *Do you think that I am going on a big complex mess ? or do you think it will be only simple modifications ?* I have also another question about the GeoPDEs toolbox. For surfaces you consider that we are necessarily in 2D and volume is for 3D. *Why does GeoPDEs cannot deal with 3D surfaces meaning that the physical points are in 3d space but knots are only on U and V directions ?* I try to consider my 3D surface as a volume with no depth but I got some bugs then from boundary condition problem (I think). Thank you very much for your help. Thanks to GeoPDEs developpers. It is very nice to have access to an open source IGA toolbox. Hope I will be able to bring my contribution on it. Sincerely Cyril Cassisa. PostDoc INRIA 
From: Rafael Vazquez <vazquez@im...>  20120220 10:22:54

Dear Alexis, if you want to evaluate the solution of one single points, it is enough to use sp_eval with a 1x1 grid, but you must give the coordinates of the point in the parametric domain. For a given point in the physical domain, you can easily compute the parametric coordinates with fsolve. Regards, Rafa Il 20/02/2012 11:00, alexis papagiannopoulos ha scritto: > Dear geopdes users, > > Since the solution is evaluated at NxN grid in the parametric domain via > sp_to_vtk command i would like know if I can evaluate the solution u at > any given point of the physical domain. > > Regards , > Alexis Papagiannopoulos >  > Try before you buy = See our experts in action! > The most comprehensive online learning library for Microsoft developers > is just $99.99! Visual Studio, SharePoint, SQL  plus HTML5, CSS3, MVC3, > Metro Style Apps, more. Free future releases when you subscribe now! > http://p.sf.net/sfu/learndevnowdev2 > _______________________________________________ > Geopdesusers mailing list > Geopdesusers@... > https://lists.sourceforge.net/lists/listinfo/geopdesusers > 
From: alexis papagiannopoulos <alexis.papagiannopoulos@gm...>  20120220 10:01:08

Dear geopdes users, Since the solution is evaluated at NxN grid in the parametric domain via sp_to_vtk command i would like know if I can evaluate the solution u at any given point of the physical domain. Regards , Alexis Papagiannopoulos 
From: Rafael Vazquez <vazquez@im...>  20120209 09:19:20

Hello, are you reducing the regularity with the degree? The regularity can never be greater than degree minus one. If that's not the problem, probably it is because you are solving with the isoparametric approach (NURBS space, NURBS geometry, see the technical report). In this case the degree of the space can't be lower than the degree of the geometry, and choosing a lower degree will not have any effect. Rafa Il 09/02/2012 09:01, shuohui yin ha scritto: > Hello all > > When I modify the cold GeoPDEs, i have a problem with refinement. > > > > in the datafile, > > degree = [3 3]; % Degree of the bsplines > > regularity = [2 2]; % Regularity of the splines > > n_sub = [9 9]; % Number of subdivisions > > nquad = [4 4]; % Points for the Gaussian quadrature rule > > > > When I change the *degree[]* less than 3, the function *kntrefine* and * > nrbkntins* have no affect with it. > > I do not know why? > > > > > > Thanks for your advice! > 
From: shuohui yin <shuohuiyin@gm...>  20120209 08:01:20

Hello all When I modify the cold GeoPDEs, i have a problem with refinement. in the datafile, degree = [3 3]; % Degree of the bsplines regularity = [2 2]; % Regularity of the splines n_sub = [9 9]; % Number of subdivisions nquad = [4 4]; % Points for the Gaussian quadrature rule When I change the *degree[]* less than 3, the function *kntrefine* and * nrbkntins* have no affect with it. I do not know why? Thanks for your advice! 
From: Rafael Vazquez <vazquez@im...>  20120207 13:48:32

Hi Dominik, the GNU GPL license allows you to publish any modified version of the code. The modified version must be covered by the GPL license, and you must place your name in the code. I think you have done both things, so it seems ok to me. About the example, I would replace every "#" with "%", to make it compatible with Matlab. And instead of modifying the 15 lines example I'd rather use the function "solve_laplace_", like most of the examples in the code. But that is up to you, of course. Regards, Rafa Il 07/02/2012 13:27, Dominik Mokriš ha scritto: > Hello all, > after reading the website of GeoPDEs I still don't understand one > thing, sorry if the question has been already answered: > In case I make an example of a source code by modifying your code > (adding a different geometry to example in 15 lines for instance) and > would like to make it accessible from my website, what should I do > with the license? I don't want to hurt anyone. > > To be more particular, if I begin the document with the following, > would it be enough? Where can I find other information? > > " > # LAPLACE_CIRCLE_FINAL: Short example of Laplace equation on a circle. > > # Example to solve the problem > # > #  div ( grad (u)) = 4 in Omega > # u = 0 on Gamma_D > % > % with Omega = x^2 + y^2<= 1; > % and exact solution u = 1  x^2  y^2; > % > % This program is free software: you can redistribute it and/or modify > % it under the terms of the GNU General Public License as published by > % the Free Software Foundation, either version 3 of the License, or > % (at your option) any later version. > > % This program is distributed in the hope that it will be useful, > % but WITHOUT ANY WARRANTY; without even the implied warranty of > % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > % GNU General Public License for more details. > % > % You should have received a copy of the GNU General Public License > % along with this program. If not, see<http://www.gnu.org/licenses/>;. > > # 21.9.2011 Dominik Mokris, Charles University in Prague. > # According to the examples in the article > # C. De Falco, A. Reali, R. Vazquez > # GeoPDEs: a research tool for IsoGeometric Analysis of PDEs > " > > Thanks for your advice and sorry once again, if the question has > already been answered somewhere. > Dominik Mokriš, Charles University in Prague > > 
From: Dominik Mokriš <dominik.tramvaj@gm...>  20120207 12:27:52

Hello all, after reading the website of GeoPDEs I still don't understand one thing, sorry if the question has been already answered: In case I make an example of a source code by modifying your code (adding a different geometry to example in 15 lines for instance) and would like to make it accessible from my website, what should I do with the license? I don't want to hurt anyone. To be more particular, if I begin the document with the following, would it be enough? Where can I find other information? " # LAPLACE_CIRCLE_FINAL: Short example of Laplace equation on a circle. # Example to solve the problem # #  div ( grad (u)) = 4 in Omega # u = 0 on Gamma_D % % with Omega = x^2 + y^2 <= 1; % and exact solution u = 1  x^2  y^2; % % This program is free software: you can redistribute it and/or modify % it under the terms of the GNU General Public License as published by % the Free Software Foundation, either version 3 of the License, or % (at your option) any later version. % This program is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the % GNU General Public License for more details. % % You should have received a copy of the GNU General Public License % along with this program. If not, see <http://www.gnu.org/licenses/>;. # 21.9.2011 Dominik Mokris, Charles University in Prague. # According to the examples in the article # C. De Falco, A. Reali, R. Vazquez # GeoPDEs: a research tool for IsoGeometric Analysis of PDEs " Thanks for your advice and sorry once again, if the question has already been answered somewhere. Dominik Mokriš, Charles University in Prague 