code 34142;
    comment MCA 2302;
    procedure TFMPREVEC(A, N); value N; integer N; array A;
    begin integer I, J, J1, K; real AB;

        J1:= 1;
        for J:= 2 step 1 until N do 
        begin for I:= 1 step 1 until J1 - 1 ,
            J step 1 until N do A[I,J1]:= 0;
            A[J1,J1]:= 1; AB:= A[J,J];
            if AB < 0 then 
            for K:= 1 step 1 until J1 do 
            ELMCOL(1, J1, K, J, A, A,
            TAMMAT(1, J1, J, K, A, A) * AB); J1:= J
        end;
        for I:= N - 1 step -1 until 1 do 
        A[I,N]:= 0; A[N,N]:= 1
    end TFMPREVEC

        eop