In this example mesh adaptation is performed to capture the function
that has a very sharp front. Visualization is made with plot and medit, error f-fh is computed and plotted according to each new mesh.
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Surface z=f(x,y) | 3D view of the mesh | Function and final mesh |
download example: aaa-adp.edp or return to 2D examples
real eps = 0.0001; real h=1; real hmin=0.000005; real val=10; real coef=50; // err = 1/100 int nbiter=6,firstplot=3; func f = y*x*x+y*y*y+h*tanh(val*(sin(5.0*y)-2.0*x)); cout << atanh(1) << endl; func fx = .0*y*x-0.2E1*h*(1.0-pow(tanh(val*(sin(0.5E1*y)-0.2E1*x)),2.0))*val; func fy = x*x+3.0*y*y+0.5E1*h*(1.0-pow(tanh(val*(sin(0.5E1*y)-0.2E1*x)),2.0))*val*cos(0.5E1*y); func fxy = 2.0*(x*pow(cosh(val*sin(5.0*y)-2.0*val*x),3.0)+10.0*h*val*val*cos(5.0*y) *sinh(val*sin(5.0*y)-2.0*val*x))/pow(cosh(val*sin(5.0*y)-2.0*val*x),3.0); func fxx= 2.0*(y*pow(cosh(val*sin(5.0*y)-2.0*val*x),3.0)-4.0*h*val*val *sinh(val*sin(5.0*y)-2.0*val*x))/pow(cosh(val*sin(5.0*y)-2.0*val*x),3.0); func d = fx*fy - fxy*fxy; func fyy=(6.0*y*pow(cosh(val*sin(5.0*y)-2.0*val*x),3.0)-50.0*h*val*val* pow(cos(5.0*y),2.0)*sinh(val*sin(5.0*y)-2.0*val*x)-25.0*h*val*sin(5.0*y)*cosh(val* sin(5.0*y)-2.0*val*x))/pow(cosh(val*sin(5.0*y)-2.0*val*x),3.0); border cercle(t=0,2*pi){ x=cos(t);y=sin(t);} mesh Th=buildmesh(cercle(20)); fespace Ph(Th,P0); fespace Vh(Th,P1); fespace V2h(Th,P2); Vh fh=f; plot(fh,wait=0); // for (int i=0;i<nbiter;i++) { // Th=adaptmesh(Th,f); verbosity=4; Vh fxxh=fxx, fxyh=fxy, fyyh = fyy; cout << " min max f_xx : " << fxxh[].min << " " << fxxh[].max << endl; cout << " min max f_yy : " << fyyh[].min << " " << fyyh[].max << endl; cout << " min max f_xy : " << fxyh[].min << " " << fxyh[].max << endl; Th=adaptmesh(Th,fxx*coef,fxy*coef,fyy*coef,IsMetric=1,nbvx=10000,hmin=hmin,ratio = 5, nbsmooth = 0, omega = 1); fh=f; Ph e=log10(abs(fh-f)); Vh dh=(d>0)*2-1; plot(Th,fh,dh); real[int] vviso(20); for (int i=0;i<20;i++) vviso[i]=(-20+i)/2.; cout << " min max fh " << fh[].min << " " << fh[].max << endl; cout << " min max log(e) " << e[].min << " " << e[].max << endl; if (i>=firstplot) { plot(e,fill=1,value=1,wait=0,viso=vviso,cmm="log10(e) err="+1./coef); savemesh(Th,"Thh"+i+".mesh"); savemesh(Th,"Th"+i,[x,y,fh/2]); { Vh eh=e; ofstream file("Th"+i+".BB"); file << "2 1 1 "<< fh[].n << " 2 \n"; int j; for (j=0;j<fh[].n ; j++) { file << eh[][j] << endl; } } exec("ffmedit `pwd`/Th"+i); } }
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