Обратная матрица

[helena91]

написала программу, которая виполняет операции над матрицами и почему то обратную матрицу находит неверно. помогите найти ошыбку. вот процедурки для вычисления:

procedure inversm(var x,obr:matrix;err:boolean);
var y:matrix; i,j:integer;
procedure swaps(i,j:integer);
var k:integer; p:TM;
procedure swap(a,b:TM);
var c:TM;
begin c:=a; a:=b; b:=c end;
begin
for k:=1 to ng do begin swap(x[i,k],x[j,k]); swap(y[i,k],y[j,k]) end;
end;
procedure adds(i,j:integer;alpha:TM);
var k:integer;
begin
for k:=1 to ng do
begin x[i,k]:=x[i,k]+x[j,k]*alpha; y[i,k]:=y[i,k]+y[j,k]*alpha
end end;
procedure divs(i:integer;alpha:TM);
var k:integer;
begin
if alpha<>0 then
for k:=1 to ng do
begin
x[i,k]:=x[i,k]/alpha; y[i,k]:=y[i,k]/alpha end
end;
begin
for i:=1 to ng do
for j:=1 to ng do y[i,j]:=0;
for i:=1 to ng do y[i,i]:=1;
{початок основного методу}
for j:=1 to ng-1 do
begin
i:=j;
while x[i,j]=0 do i:=i+1;
if i>ng then begin err:=true; end;
swaps(j,i);
for i:=j+1 to ng do begin if x[j,j]=0 then err:=true else
adds(i,j,-x[i,j]/x[j,j]); end;
end;
if x[ng,ng]=0 then begin err:=true; end;
for i:=1 to ng do divs(i,x[i,i]);
for i:=ng downto 2 do
for j:=i-1 downto 1 do adds(j,i,-x[j,i]);
{сформульована обернена}
obr:=y;
end;
procedure readm(var x:matrix);
var i,j,ti:integer;
begin repeat text1(bbb);
rx:=4; ry:=4; rz:=1;
readword2(rr,rx,ry,rz); ti:=rr; clrscr;
if (ti=1) then begin textcolor(lightblue); Frame(xx,yy,zz,ii); gotoxy(4,2);
for i:=1 to ng do begin
for j:=1 to ng do begin textcolor(lightgreen); write('Enter elements of matrix',i,'_',j,': ');
rx:=4; ry:=3; rz:=3;
readword2(rr,rx,ry,rz); x[i,j]:=rr; clrscr; textcolor(lightblue); Frame(xx,yy,zz,ii); gotoxy(4,2);
end; end; end;
if (ti=2) then begin
randomize;
for i:=1 to ng do begin
for j:=1 to ng do begin x[i,j]:=random(20); end; end; end;
until (ti>=1) and (ti<=2); clrscr; textcolor(lightblue); Frame(xx,yy,zz,ii); gotoxy(4,2);
textcolor(lightgreen); writeln('Start matrix:');
for i:=1 to ng do begin gotoxy(4,2+i); textcolor(white);
for j:=1 to ng do write(x[i,j]:8:2); writeln; end;
end;
procedure writem(var x:matrix);
var i,j:integer;
begin writeln; gotoxy(4,6+2*ng); textcolor(lightgreen); writeln('Inverse matrix:');
for i:=1 to ng do
begin gotoxy(4,6+2*ng+i);textcolor(lightc yan);
for j:=1 to ng do write(x[i,j]:8:2,' ');
writeln; end;
end;

Ето вывод в case:
2: begin {Обернена матриця}
Repeat textbackground(black); clrscr; textcolor(lightblue); Frame(xx,yy,zz,ii); gotoxy(4,2); textcolor(lightgreen); write('Enter degree of matrix: '); rx:=4; ry:=3; rz:=1; readword2(rr,rx,ry,rz); ng:=rr; gotoxy(4,5);
if (ng<=1) or (ng>5) then writeln('Error!!!') else begin
begin
readm(x); inversm(x,y,err);
end;
for ir:=1 to ng do
for jr:=1 to ng do begin
z[ir,jr] := 0;
for i:= 1 to ng do
{Підсумкова формула}
z[ir,jr] :=z[ir,jr] + x[ir,i] * x[i,jr];
end;
begin
writeln; gotoxy(4,4+ng); textcolor(yellow); writeln('Checking: it must be unitary matrix.'); textcolor(lightcyan);
for ir:=1 to ng do begin gotoxy(4,4+ng+ir);
for jr:=1 to ng do
Write(z[ir,jr]:8:2); WriteLn; end;
end;
writeln; textcolor(lightgreen);
for ir:=1 to ng do
for jr:=1 to ng do begin
if ((ir=jr) and (z[ir,jr]<>1)) or ((ir<>jr) and (z[ir,jr]<>0)) then
l1:=1; end; gotoxy(4,10+2*ng);textcolor(lightre d);
if (l1=1) then writeln('Inverse matrix not exist!')
else writem(y);
end; text(bbb);
ch:=readkey;
if ch=#0 then ch:=readkey;
until ch=#27;
end;


Если нужно, могу скинуть весь исходник.