> restart;
> with(LinearAlgebra):
> #Gauss-Elimination mit Ueberschreiben von A, Spaltenpivot
> gaussSP:=proc(A) 
> global p;  # p speichert die Zeilenvertauschungen
> local n,m,piv,pivj,j,k,x; 
> n:=RowDimension(A); 
> p:=vector(n, i->i); 
> for m from 1 by 1 to n do  
>    piv:= abs(A[m,m]); 
>    pivj:= m; 
>    for j from m+1 by 1 to n do 
>       if abs(A[j,m]) > piv then piv := abs(A[j,m]); 
>          pivj:=j 
>       end if; 
>    end do; 
>    k:=p[m]; p[m]:=p[pivj]; p[pivj] :=k; 
>    for k from 1 by 1 to n do 
>       x[k]:=A[m,k]; A[m,k]:=A[pivj, k]; A[pivj,k]:= x[k] 
>    end do; 
>    for j from m+1 by 1 to n do A[j,m]:=A[j,m]/A[m,m];  
>       for k from m+1 by 1 to n do A[j,k]:=A[j,k]- A[j,m]*A[m,k] end do 
>    end do; 
> end do;  
> evalm(A) 
> end proc:
> A:=Matrix([[6.,7.,0.,1.,2.,5.],[13.,4.,2.,4.,5.,3.],[6.,2.,3.,6.,8.,9.],[1.,3.,0.,0.,2.,4.],[1.,1.,3.,5.,7.,9.],[0.,0.,4.,5.,0.,2.]]);
> gaussSP(A);
> 
>