Программирование матричных операций

program lab5;
var a:array [1..10,1..10] of real;
    x:array [1..10] of real;
    i,j,k,n: integer;
    y,s,c,max,min: real;
begin
write ('n='); read(n);
     {---????? 1---}
for i:=1 to n do
for j:=1 to n do
a[i,j]:=(10*i+25*j)/(5*i*j);
writeln(' ':20,'matrix A');
for i:=1 to n do
begin
for j:=1 to n do
write(a[i,j]:8:3);
writeln;
end;
  {---????? 2---}
for i:=1 to n do
begin
s:=0;
for j:=1 to n do s:=s+min(a[i,j],a[i,j+1])+ max(a[j,i],a[j,j+1])/2;
x[i]:= min(a[i,j],a[i,j+1])+ max(a[j,i],a[j,j+1])/2;
end;
writeln ('':20,'vector x');
for i:=1 to n do write (x[i]:8:3);
  {---????? 3---}
for i:=1 to n-1 do
begin
k:=i;
for j:=i+1 to n do
if odd(j) then
if odd(i) then
if a[j,j]>a[i,j] then
k:=j;
if i<>k then
begin
c:=a[i,j];a[i,j]:=a[k,j];
a[k,j]:=c;
end;
end;
writeln ('':20,'????????????? ???????');
for i:=1 to n do begin
for j:=1 to n  do
write(a[i,j]:8:3);
writeln;
end;
    {---????? 4---}
s:=0;
for i:=1 to n-1 do begin
if odd(i) then
s:=s + x[i]*x[n+1-i];
y:=s;
end;
writeln('y=',y:4:1);
end.