Freefem+ Home Page (24-oct-1999)

FreeFem+

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This version the the freefem language is obsolete, the new language is FreeFem++. The new language is not compatible, but it's possible to play we lots of finite elements types P^0, P^1,P^2, RT, P1nc.

FreeFem+ is an implementation of a language dedicated to the finite element method. It provides you a way to solve Partial Differential Equations (PDE) simply. Problems involving partial differential equations (pde) of several branches of physics such as fluid-structure interactions require interpolations of data on several meshes and their manipulation within one program. In this report we build on a fast quadtree-based interpolation algorithm, propose a language for the manipulation of data on multiple meshes (generated with bamg) and test by designing an extension of freefem.
FreeFem+ is written in a C++ idioms, this software run on all unix computted with X11, and under Window95, 98, NT, and MacOs 9 and X .

You may ask questions, send comments or bug reports to Frédéric Hecht .

the FreeFem+ team is: Olivier Pironneau , Frédéric Hecht, Domique Bernardi, Kohji Ohtsuka , Thomas Lachand-Robert

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A very small example of what you can do to solve Poisson equation on L shape.

border a(t=0,1){x=t;y=0};
border b(t=0,0.5){x=1;y=t};
border c(t=0,0.5){x=1-t;y=0.5};
border d(t=0.5,1){x=0.5;y=t};
border e(t=0.5,1){x=1-t;y=1};
border f(t=0,1){x=0;y=1-t};
mesh th = buildmesh ( a(6) + b(4) + c(4) +d(4) + e(4) + f(6));
err := 0.1;coef := 0.1^(1./5.); // divide by 10 the level of error in 5 iteration
for i= 1 to 5 do
{
   solve(u) {
   pde(u) -laplace(u) = 1;
   on(a,b,c,d,e,f) u=0;}
   mesh th = adaptmesh (th,u) err=err, nbvx=5000 ;
};

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