高斯消元模板（pascal）

洛谷P3389评测

 program rrr(input,output);
 const
   eps=1e-8;
 var
   a:array[..,..]of double;
   n,i,j,k:longint;
   t:double;
 begin
    assign(input,'r.in');assign(output,'r.out');reset(input);rewrite(output);
    readln(n);
    for i:= to n do for j:= to n+ do read(a[i,j]);
    for i:= to n do
       begin
          k:=i;
          for j:=i+ to n do if abs(a[j,i])>abs(a[k,i]) then k:=j;
          if abs(a[k,i])<eps then begin write('No Solution');close(input);close(output);halt; end;
          for j:=i to n+ do begin t:=a[i,j];a[i,j]:=a[k,j];a[k,j]:=t; end;
          t:=a[i,i];for j:=i to n+ do a[i,j]:=a[i,j]/t;
          for j:= to n do
             if j<>i then
                begin
                   t:=a[j,i];
                   for k:=i to n+ do a[j,k]:=a[j,k]-a[i,k]*t;
                end;
       end;
    for i:= to n do writeln(a[i,n+]::);
    close(input);close(output);
 end.