Метод Либмана

program DifurEllips;
uses Crt;
Const
n= 10;
m=10;
e=0.001;
h=1;
l=1;
var 
u:array[0..60,0..60] of Real;
i,j,it,m1,n1:Integer;
r,d,unew:Real;
p:Boolean;
procedure Libman;
var i,j:Integer;
Begin
p:=False;
for i:=1 to m1-1 do begin
for j:=1 to n1-1 do begin
uNew:=0/25*(u[i+1,j]+u[i-1,j]+u[i,j-1]+u[i,j+1]);
d:=Abs(unew-u[i,j]);
if d>e then
p:=True;
u[i,j]:=unew;
end;
end;
End;

function F1(x:Real):real;
begin
F1:=-Sqr(x);
end;
function F2(x:Real):real;
begin
F2:=16+8*x-sqr(x);
end;
function F3(x:Real):real;
begin
F3:=Sqr(x);
end;
function F4(x:Real):real;
begin
F4:=sqr(x)+6*x-9;
end;

BEGIN
ClrScr;
n1:=Trunc(n/h);
m1:=Trunc(m/l);
for i:=1 to m1 do
for j:=1 to n1 do
u[i,j]:=0;
for j:=0 to m1 do
u[0,j]:=F1(j*h);
for j:=0 to m1 do
u[n1,j]:=F2(j*h);
for i:=1 to n1 do
u[i,0]:=F3(i*h);
for i:=1 to n1 do
u[i,m1]:=F4(i*h);

Libman;
it:=1;
while p and (it<100) do begin
libman;
it:=it+1;
end;
writeln('Rezyltati vichisleniy');
write('');
for j:=0 to n1 do
write(j*h:2,'');
Writeln();
Writeln();
for i:=m1 downto n do begin
write('',i*l:2,'|');
for j:=0 to n1 do begin
write(u[i,j]:3:2,'');
Writeln('');
end;
end;
Writeln('');
Writeln(' ');
for j:=0 to n1 do 
Write(j*h:2,' ');
Writeln('');
Writeln('');
Writeln(' Chislo iterashiy: ',it:2);
Writeln(' Pogreshnost e= ',e:1:3);
while not keypressed do;
END.