[Gmsh] spline implementation

[Marek Wojciechowski]

Dnia środa, 12 marca 2014 21:02:09 Marek Wojciechowski pisze:
> Hi!
> 
> I'm working now on some code which uses gmsh to mesh surfaces given by
> single, closed Spline loop. However actually i do not know how the splines
> work in gmsh. For example, i expected that the script:
> 
> Point(1) = {1.0, 0.0, 0.0};
> Point(2) = {0.0, 1.0, 0.0};
> Point(3) = {-1.0, 0.0, 0.0};
> Point(4) = {0.0, -1.0, 0.0};
> Spline(1) = {1, 2, 3, 4, 1};
> Line Loop(1)={1};
> Plane Surface(1) = {1};
> 
> will give me a result quite close to circle. At least, for 3rd order spline
> interpolation (separately interpolated x and y with the same evenly spaced
> parameter and with periodic boundary) the result is much closer to circle.
> So may question is, how the spline curves are implemented in gmsh?

After some investigations i'm now sure that splines in gmsh, are *not* the 
"natural" splines as described for example in:

http://mathworld.wolfram.com/CubicSpline.html

Is it possible that only boundary condition Y'' = 0 is taken differently in 
gmsh. Please anyone can give me a clue what kind of splines are in use here?

Regards,
-- 
Marek Wojciechowski 
Katedra Geotechniki i Budowli Inżynierskich P.Ł. (K-66)
Al. Politechniki 6
90-924 Łódź
Telefon: +0048 42 6313590
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