Asking for help for solving nonlinear elliptic 2D

Dear all,

I try to solve the nonlinear elliptic equation .

with the boundary define like

Neuman condtion at Edge 1 =constant

Neuman condtion at Edge 2 4= 0

Dirchlet condtion at Edge E3 =0;

Moreover, the coeffcients c is zero at Nb and one at other node.

coefficinet a=0;

f=0;

Please help me by showing how can I define the ceofficient and the boudary.

The code for the problem geometry is like this

____________________________________

clc;

clear all

global Nb

rect1 = [3

4

0

1

1

0

0

0

1

1];

ns = char('rect1');

ns = ns';

sf = 'rect1';

gd=rect1;

g = decsg(gd,sf,ns);

model = createpde;

geometryFromEdges(model,g);

figure(1)

pdegplot(model,'EdgeLabels','on')

axis equal

xlim([-0.1,1.1])

ylim([-0.1,1.1])

mesh = generateMesh(model,'Hmax',0.05)

figure(2)

Nb = findNodes(mesh,'box',[0 0.5],[0.5-0.05/2 0.5+0.05/2]);

pdemesh(model)

hold on

plot(mesh.Nodes(1,Nb),mesh.Nodes(2,Nb),'or','MarkerFaceColor','g')

___________________________________

Thank you very much.

Sincerely,

Pham L.T. Duong