Алгоритм решения СЛАУ методом Гаусса

 PROCEDURE SIMQ(Nn:Integer;Var Aa:TMatr;Var Bb:TVector;Var Ks:Integer);
Label M1;
Const Eps=1e-21;
Var Max,U,V : Real; I,J,K1,L : Integer;
Begin
For I:=1 To Nn Do Aa[i,Nn+1]:=Bb[i];
For I:=1 To Nn Do
 Begin
 Max:=Abs(Aa[i,i]); K1:=I;
 For L:=I+1 To Nn Do If (Abs(Aa[l,i])>Max) Then
 Begin
 Max:=Abs(Aa[l,i]); K1:=L;End;
 If(Max<Eps) Then Begin Ks:=1; Goto M1;
 End Else Ks:=0; 
 If K1<>I Then
 For J:=I To Nn+1 Do
 Begin U:=Aa[i,j]; Aa[i,j]:=Aa[k1,j]; Aa[k1,j]:=U; End;
 V:=Aa[i,i];
 For J:=I To Nn+1 Do Aa[i,j]:=Aa[i,j]/V;
 For L:=i+1 To Nn Do Begin
 V:=Aa[l,i]; For J:=I+1 To Nn+1 Do Aa[l,j]:=Aa[l,j]-Aa[i,j]*V;
 End; End;
 Bb[nn]:=Aa[Nn,Nn+1];
 For I:=Nn-1 Downto 1 Do Begin Bb[i]:=Aa[i,nn+1];
 For J:=I+1 To Nn Do Bb[i]:=Bb[i]-Aa[i,j]*Bb[j];
 End;
 M1:End;

const
  sz = 10;
 
type
  TVector = array [1 .. sz] of real;
  TMatr = array [1..sz] of TVector;

const
  sz = 3;
 
type
  TVector = array [1 .. sz] of real;
  TMatr = array [1..sz] of TVector;
 
PROCEDURE SIMQ(Nn:Integer;Var Aa:TMatr;Var Bb:TVector;Var Ks:Integer);
  Const Eps=1e-21;
  Var
    I,J,k : Integer;
    x: TVector;
    h: real;
begin
  Ks:=1;
  if abs(Aa[Nn,Nn])<Eps then
      exit;
  //Прямой ход - исключение переменных
  for i:=1 to Nn-1 do
    for j:=i+1 to Nn do
    begin
      if abs(Aa[i,i])<Eps then
        exit;
      Aa[j,i]:=-Aa[j,i]/Aa[i,i];
      for k:=i+1 to Nn do
        Aa[j,k]:=Aa[j,k]+Aa[j,i]*Aa[i,k];
      Bb[j]:=Bb[j]+Aa[j,i]*Bb[i]
    end;
  x[Nn]:=Bb[Nn]/Aa[Nn,Nn];
  //Обратный ход - нахождение корней
  for i:=Nn-1 downto 1 do
  begin
    h:=Bb[i];
    for j:=i+1 to Nn do
      h:=h-x[j]*Aa[i,j];
    x[i]:=h/Aa[i,i]
  end;
  Bb:=x;
  Ks:=0;
end;
 
PROCEDURE test;
const
  ac : TMatr = ( (1,1,1),(1,0,-1),(1,2,1));
  bc : TVector = (6,-2,8);
var
  a : TMatr;
  b : TVector;
  ks: integer;
begin
  a:=ac; b:=bc;
  SIMQ(sz,a,b,ks);
  if ks<>0 then
    writeln('error')
  else begin 
    for var I := 1 to sz  do
    begin
      write(b[i]);
      write('   ');
    end;
    writeln;  
  end;  
end;
 
begin
  test;
end.

uses GraphABC; 
const
  Angle = -Pi / 4;
 
procedure RLine(x, y, x1, y1: real):=Line(Round(x), Round(y), Round(x1), Round(y1)); 
 
procedure Draw(x, y, l: real; iterations: integer);
begin
  var lx := x + l * Cos(Angle);
  var ly := y + l * Sin(Angle);
  
  var angle1 := -Pi / 2 + Angle;
  var rx := x + l * Cos(angle1);
  var ry := y + l * Sin(angle1);
  
  RLine(x, y, lx, ly); 
  RLine(x, y, rx, ry);
  
  if iterations > 0 then 
  begin
    Dec(iterations);
    l := l / 2; 
    Draw(lx, ly, l, iterations); 
    Draw(rx, ry, l, iterations); 
  end; 
end;
 
begin
  Lockdrawing();
  Draw(300, 300, 200, 7);
  Redraw();
end.