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{ Old file: tbs0016.pp }
{ }
{ %skiptarget=wince }
uses
crt;
const
{ ... parameters }
w = 10; { max. 10 }
h = 10; { max. 10 }
type
tp = array[0..w,0..h] of double;
var
temp : tp;
phi : tp;
Bi : tp;
boundary : array[0..w,0..h] of double;
function start_temp(i,j : longint) : double;
begin
start_temp:=(boundary[i,0]*(h-j)+boundary[i,h]*j+boundary[0,j]*(w-i)+boundary[w,j]*i)/(w+h);
end;
procedure init;
var
i,j : longint;
begin
for i:=0 to w do
for j:=0 to h do
temp[i,j]:=start_temp(i,j);
end;
procedure draw;
var
i,j : longint;
begin
for i:=0 to w do
for j:=0 to h do
begin
textcolor(white);
gotoxy(i*7+1,j*2+1);
writeln(temp[i,j]:6:0);
textcolor(darkgray);
gotoxy(i*7+1,j*2+2);
writeln(phi[i,j]:6:3);
end;
end;
procedure calc_phi;
var
i,j : longint;
begin
for i:=0 to w do
for j:=0 to h do
begin
if (i=0) and (j=0) then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+0.5*temp[i,j+1]+0.5*temp[i+1,j]-(1+Bi[i,j])*temp[i,j];
end
else if (i=0) and (j=h) then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+0.5*temp[i,j-1]+0.5*temp[i+1,j]-(1+Bi[i,j])*temp[i,j];
end
else if (i=w) and (j=0) then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+0.5*temp[i,j+1]+0.5*temp[i-1,j]-(1+Bi[i,j])*temp[i,j];
end
else if (i=w) and (j=h) then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+0.5*temp[i,j-1]+0.5*temp[i-1,j]-(1+Bi[i,j])*temp[i,j];
end
else if i=0 then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+temp[i+1,j]+0.5*temp[i,j-1]+0.5*temp[i,j+1]-(2+Bi[i,j])*temp[i,j];
end
else if i=w then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+temp[i-1,j]+0.5*temp[i,j-1]+0.5*temp[i,j+1]-(2+Bi[i,j])*temp[i,j];
end
else if j=0 then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+temp[i,j+1]+0.5*temp[i-1,j]+0.5*temp[i+1,j]-(2+Bi[i,j])*temp[i,j];
end
else if j=h then
begin
phi[i,j]:=Bi[i,j]*boundary[i,j]+temp[i,j-1]+0.5*temp[i-1,j]+0.5*temp[i+1,j]-(2+Bi[i,j])*temp[i,j];
end
else
phi[i,j]:=temp[i,j-1]+temp[i-1,j]-4*temp[i,j]+temp[i+1,j]+temp[i,j+1];
end;
end;
procedure adapt(i,j : longint);
begin
if (i=0) and (j=0) then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+0.5*temp[i,j+1]+0.5*temp[i+1,j])/(1+Bi[i,j]);
end
else if (i=0) and (j=h) then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+0.5*temp[i,j-1]+0.5*temp[i+1,j])/(1+Bi[i,j]);
end
else if (i=w) and (j=0) then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+0.5*temp[i,j+1]+0.5*temp[i-1,j])/(1+Bi[i,j]);
end
else if (i=w) and (j=h) then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+0.5*temp[i,j-1]+0.5*temp[i-1,j])/(1+Bi[i,j]);
end
else if i=0 then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+temp[i+1,j]+0.5*temp[i,j-1]+0.5*temp[i,j+1])/(2+Bi[i,j]);
end
else if i=w then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+temp[i-1,j]+0.5*temp[i,j-1]+0.5*temp[i,j+1])/(2+Bi[i,j]);
end
else if j=0 then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+temp[i,j+1]+0.5*temp[i-1,j]+0.5*temp[i+1,j])/(2+Bi[i,j]);
end
else if j=h then
begin
temp[i,j]:=(Bi[i,j]*boundary[i,j]+temp[i,j-1]+0.5*temp[i-1,j]+0.5*temp[i+1,j])/(2+Bi[i,j]);
end
else
temp[i,j]:=(temp[i,j-1]+temp[i-1,j]+temp[i+1,j]+temp[i,j+1])/4;
end;
var
iter,i,j,mi,mj : longint;
habs,sigma_phi : double;
begin
clrscr;
iter:=0;
{ setup boundary conditions }
for i:=0 to w do
for j:=0 to h do
begin
if (i=0) or (i=w) then
bi[i,j]:=100
else
bi[i,j]:=100;
if (j=0) then
boundary[i,j]:=1000
else
boundary[i,j]:=300;
end;
init;
draw;
repeat
calc_phi;
mi:=0;
mj:=0;
sigma_phi:=0;
inc(iter);
habs:=abs(phi[mi,mj]);
for i:=0 to w do
for j:=0 to h do
begin
if abs(phi[i,j])>habs then
begin
mi:=i;
mj:=j;
habs:=abs(phi[mi,mj]);
end;
{ calculate error }
sigma_phi:=sigma_phi+abs(phi[i,j]);
end;
adapt(mi,mj);
gotoxy(1,23);
textcolor(white);
writeln(iter,' iterations, sigma_phi=',sigma_phi);
until {keypressed or }(sigma_phi<0.5);
draw;
gotoxy(1,23);
textcolor(white);
writeln(iter,' iterations, sigma_phi=',sigma_phi);
{writeln('press a key');
if readkey=#0 then
readkey;}
end.
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