There is nothing you can do about this other than not rely on differences thatĪre this small relative to the absolute size of the numbers. Number significantly (relative to the differences between numbers you are Representable floating point number, and this rounding operation changes the More like integers because every operation involves rounding to the next If you have numbers where you depend on differences at the level of round-off,Īrithmetic works very differently than for regular real numbers. Have are at approximately at the level of round-off, and any computation youĭo with these numbers will add to the effect of round-off. No, this is round-off error in action :-) Floating point numbers have onlyĪpproximately 16 digits of accuracy. > Now it works again.this is mind-blowing. Please let me know if I can provide some more useful information. Just something wrong occurs when parsing the values. Interesting enough, the mapping will fail again.Īnother test: I add say two random digits to each vertex coordinate: However, if we try one of the following, as example: If we approximate the value to 0.49999999999882 2 the mapping will be ok. So, let's just consider the coordinate y1. The vertexes of cell 0 are the following: msh file is made of two cells: the one with index 0 which is wrong and one of its neighbours, with index 1, which is ok. Yes, exactly, if the entries were parsed as you mentioned everything would work fine.īut unfortunately I guess this is not the case. May you please help me? I would really appreciate it. The same apply if you pick an other real point within this cell. I would expect that the coordinates of the unit point are x=0.5, y=0.5.
#GMSH MESH.RANDOM FACTOR CODE#
The code computes the mapped point of a generic real point which is placed in the center of a "sick" cell (id=354). I provide a small code that I am testing as well as the. For sure I am missing something but I was not able to figure out the solution to this issue. I don't see any apparent explanation to this. What concerns me the most is that this occurs only for certain "random" cells of the domain. msh file and everything looks fine for me. If I generate the same identical mesh using subdivided_hyper_rectangle instead, everything works well. What happens is that for some cell (only few cells) the function transform_real_to_unit_cell gives me a wrong result, that is the coordinates of some mapped point are not correct. Then, since I want to compute the shape functions, I need to know the position of the mapped points on the unit cell. msh file and I read in using the GridIn class. geo file (which contains "physical lines" and "physical I am facing a problem with the mapping of a point on the real cell to the unit cell when the mesh is read in from a.
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