nonuniform grid
in [Matlab]
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From: Marwa Helemish on 9 Jun 2010 09:54 "the cyclist" <thecyclist(a)gmail.com> wrote in message <huo3t9$1c8$1(a)fred.mathworks.com>... > "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo35h$b6d$1(a)fred.mathworks.com>... > > "John D'Errico" <woodchips(a)rochester.rr.com> wrote in message <huo2ao$g1q$1(a)fred.mathworks.com>... > > > "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo1kl$v6$1(a)fred.mathworks.com>... > > > > Hello everybody, > > > > I am trying to solve some of nonlinear function by using numerical methods, As you know, I first thing in the solving steps is discrization of the dimension domain, > > > > I wnat to know how can i gerenate or creat non uniform grid in 1D for example > > > > In uniform grid is more easier than nonuniform > > > > it can be done with linespace or semicolon. > > > > But for nonuniform condiction, how would the grid be discrizated? > > > > > > Since it is a NON-uniform grid, you cannot use tools > > > that build a uniform sequence of numbers. However, > > > since only you know what non-uniformity you will > > > choose, how can we possibly tell you how to build it? > > > > > > Use a loop. Or do it by hand. > > > > > > The crystal ball is foggy today. > > > > > > John > > > > Although your reply doe not satisfy my request. > > at leastplease, give me an example to nonuniform grid in 1D in matlab > > While John becomes apoplectic, here is an example of a non-uniform grid of points in one dimension: > > x = [1 2 4]; Many thanks But it seems that I did not describe my problem in the rigth way. I know exactly what it means the nonuniform grid , I have the lower and the upper limits (range) say from [1,5], I want to creat the nonuniform samples inside this interval with some specfic dense with controlling around specfic point inbetween. thanks again and non equal step.
From: Steven Lord on 9 Jun 2010 10:18 "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message news:huo6e1$n1d$1(a)fred.mathworks.com... > "the cyclist" <thecyclist(a)gmail.com> wrote in message > <huo3t9$1c8$1(a)fred.mathworks.com>... >> "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message >> <huo35h$b6d$1(a)fred.mathworks.com>... *snip* > Many thanks But it seems that I did not describe my problem in the rigth > way. > I know exactly what it means the nonuniform grid , > I have the lower and the upper limits (range) say from [1,5], I want to > creat the nonuniform samples inside this interval with some specfic dense > with controlling around specfic point inbetween. Okay ... but without knowing SPECIFICALLY what you want or need, how can we possibly help you determine how to accomplish your goal? What density function? What specific point? If there was a uniform distribution that satisfied your other requirements, would it be acceptable or would it be rejected simply due to the fact that it's uniform? The more information you provide, the more likely you are to receive a useful answer. -- Steve Lord slord(a)mathworks.com comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ To contact Technical Support use the Contact Us link on http://www.mathworks.com
From: the cyclist on 9 Jun 2010 10:25 "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo6e1$n1d$1(a)fred.mathworks.com>... > "the cyclist" <thecyclist(a)gmail.com> wrote in message <huo3t9$1c8$1(a)fred.mathworks.com>... > > "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo35h$b6d$1(a)fred.mathworks.com>... > > > "John D'Errico" <woodchips(a)rochester.rr.com> wrote in message <huo2ao$g1q$1(a)fred.mathworks.com>... > > > > "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo1kl$v6$1(a)fred.mathworks.com>... > > > > > Hello everybody, > > > > > I am trying to solve some of nonlinear function by using numerical methods, As you know, I first thing in the solving steps is discrization of the dimension domain, > > > > > I wnat to know how can i gerenate or creat non uniform grid in 1D for example > > > > > In uniform grid is more easier than nonuniform > > > > > it can be done with linespace or semicolon. > > > > > But for nonuniform condiction, how would the grid be discrizated? > > > > > > > > Since it is a NON-uniform grid, you cannot use tools > > > > that build a uniform sequence of numbers. However, > > > > since only you know what non-uniformity you will > > > > choose, how can we possibly tell you how to build it? > > > > > > > > Use a loop. Or do it by hand. > > > > > > > > The crystal ball is foggy today. > > > > > > > > John > > > > > > Although your reply doe not satisfy my request. > > > at leastplease, give me an example to nonuniform grid in 1D in matlab > > > > While John becomes apoplectic, here is an example of a non-uniform grid of points in one dimension: > > > > x = [1 2 4]; > > Many thanks > But it seems that I did not describe my problem in the rigth way. > I know exactly what it means the nonuniform grid , > I have the lower and the upper limits (range) say from [1,5], I want to creat the nonuniform samples inside this interval with some specfic dense with controlling around specfic point inbetween. > thanks again > and non equal step. Marwa, I feel as though I am torturing a prisoner, and with each strike of the whip, I get a tiny little bit more information! From the start, we have had no way of knowing how much MATLAB you know, or exactly what it is that you are trying to do. You were much too vague to get specific answers. I am not sure I can help you, but there are two things that need to be known, I think, by anyone who might help you: (1) Do you have the Stats Toolbox, and (2) what SPECIFIC distribution or distributions do you want your grid points to have? There is a thread entitled "Generating Sample from a Distribution" that may help you. I honestly don't remember all the details, but there is a method that involves using the inverse of the cumulative density function, which you can read about there. the cyclist
From: John D'Errico on 9 Jun 2010 10:28 "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo35h$b6d$1(a)fred.mathworks.com>... > "John D'Errico" <woodchips(a)rochester.rr.com> wrote in message <huo2ao$g1q$1(a)fred.mathworks.com>... > > "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo1kl$v6$1(a)fred.mathworks.com>... > > > Hello everybody, > > > I am trying to solve some of nonlinear function by using numerical methods, As you know, I first thing in the solving steps is discrization of the dimension domain, > > > I wnat to know how can i gerenate or creat non uniform grid in 1D for example > > > In uniform grid is more easier than nonuniform > > > it can be done with linespace or semicolon. > > > But for nonuniform condiction, how would the grid be discrizated? > > > > Since it is a NON-uniform grid, you cannot use tools > > that build a uniform sequence of numbers. However, > > since only you know what non-uniformity you will > > choose, how can we possibly tell you how to build it? > > > > Use a loop. Or do it by hand. > > > > The crystal ball is foggy today. > > > > John > > Although your reply doe not satisfy my request. > at leastplease, give me an example to nonuniform grid in 1D in matlab A trivial, although not terribly useful one is: primes(100) Your question does not satisfy any standards of a reasonable question. If you want a different non-uniform grid, then YOU need to specify how you will define the non-uniformity. John
From: John D'Errico on 9 Jun 2010 10:35 "Marwa Helemish" <helemish(a)iee.tu-dresden.de> wrote in message <huo6e1$n1d$1(a)fred.mathworks.com>... > > While John becomes apoplectic, here is an example of a non-uniform grid of points in one dimension: > > (Good description.) > > x = [1 2 4]; > > Many thanks > But it seems that I did not describe my problem in the rigth way. > I know exactly what it means the nonuniform grid , > I have the lower and the upper limits (range) say from [1,5], I want to creat the nonuniform samples inside this interval with some specfic dense with controlling around specfic point inbetween. > thanks again > and non equal step. Still, all that you have done is to give a vague description of your goal that is not quantified in any way mathematically. You say that you want SOME specific density of points, but not what it is. YOU may know exactly what you want, but WE are not mind readers. John
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