Program DemRelax;

USES Crt;

CONST
   np = 50;
TYPE
   RealArrayNP = ARRAY [1..np] OF real;
   RealArrayNPbyNP = ARRAY [1..np,1..np] OF real;

PROCEDURE Relax(VAR a: RealArrayNPbyNP;
                    n: integer; omg: Real;
                    VAR b, xold, xnew: RealArrayNP);
VAR i,j : integer;
    delt : Real;

BEGIN
      FOR i:= 1 TO n DO BEGIN
                 delt := b[i];
                 FOR j:= 1 TO i-1 DO
                         delt := delt - a[i,j]*xnew[j];
                 FOR j:= i TO n DO
                         delt := delt - a[i,j]*xold[j];
                 delt := delt / a[i,i];
                 xnew[i] := xold[i] + omg*delt
      END;
END;

CONST MAXK=1000;

VAR a: RealArrayNPbyNP;
    n,i,j,krok: integer;
    omg,eps,rozd,maxv, maxr: Real;
    b, xold, xnew, xodh: RealArrayNP;
    fvst,fvys:Text;
    vstnam:String;
LABEL 1;

BEGIN
    Writeln('Zadej jmeno vstupniho souboru');
    Readln(vstnam);
    ASSIGN(fvst,vstnam);
    RESET(fvst);
    Writeln('Zadej dimenzi matice');
    Readln(fvst,n);
    Writeln('Zadej matici (symetrickou s nenul.diagonalou)');
    Writeln('Metoda zarucene konverguje pro pozitivne definitni matice !');
    FOR i:=1 TO n DO BEGIN
        FOR j:=1 TO n DO Read(fvst,a[i,j]); Readln(fvst);
        FOR j:=1 TO n DO Write(a[i,j]); Writeln;
        END;
    Writeln('Zadej pravou stranu');
    FOR i:=1 TO n DO Read(fvst,b[i]);
    Readln(fvst);
    FOR i:=1 TO n DO Write(b[i]);
    Writeln;
    Writeln('Dej Enter');
    Readln(fvst);
    Writeln('Zadej odhad reseni');
    FOR i:=1 TO n DO Read(fvst,xodh[i]);
    Readln(fvst);
    While true DO BEGIN
        Writeln (' Zadej omg = relax faktor, eps = relat.pres');
        Writeln (' omega = 0 nebo eps = 0 konci ukazku');
        Readln(omg,eps);
        IF omg*eps = 0 THEN GOTO 1;
        FOR i:=1 TO n DO xold[i] := xodh[i];
        krok := 0;
        REPEAT
            krok := Krok + 1;
            Relax(a,n,omg,b,xold,xnew);
            Writeln (' KROK = ', krok);
            Writeln;Write('xold ');
            FOR i:=1 TO n DO Write( xold[i]);
            Writeln;Write('xnew ');
            FOR i:=1 TO n DO Write( xnew[i]);
            Writeln;Writeln;
            maxr:=0; maxv:= 0;
            FOR i:=1 TO n DO BEGIN
                   IF abs(xnew[i]-xold[i]) > maxr THEN
                               maxr := abs(xnew[i]-xold[i]);
                   IF abs(xnew[i]) > maxv THEN maxv := abs(xnew[i]);
            END;
            Writeln('MaxRoz    = ',maxr,    '   MaxXnew  = ',maxv);
            Writeln('rel.chyba = ',maxr/maxv,'   zad.pres.= ',eps);
            Readln;
            FOR i:=1 TO n DO xold[i] := xnew[i];
        UNTIL (maxr/maxv < eps) or (Krok >= maxk);
    END;
1:
END.