"CODE" 34160;
    "INTEGER" "PROCEDURE" QRIVALSYMTRI(D, BB, N, EM); "VALUE" N;
    "INTEGER" N; "ARRAY" D, BB, EM;
    "BEGIN" "INTEGER" I, I1, LOW, OLDLOW, N1, COUNT, MAX;
        "REAL" BBTOL, BBMAX, BBI, BBN1, MACHTOL, DN, DELTA, F, NUM,
        SHIFT, G, H, T, P, R, S, C, OLDG;
        BBTOL:= (EM[2] * EM[1]) ** 2; MACHTOL:= EM[0] * EM[1];
        MAX:= EM[4]; BBMAX:= 0; COUNT:= 0; OLDLOW:= N;
        "FOR" N1:= N - 1 "WHILE" N > 0 "DO"
        "BEGIN"
            "FOR" I:= N, I - 1 "WHILE" ("IF" I >= 1 "THEN"
            BB[I] > BBTOL "ELSE" "FALSE") "DO" LOW:= I;
            "IF" LOW > 1 "THEN" "BEGIN" "IF" BB[LOW-1] > BBMAX "THEN"
            BBMAX:= BB[LOW-1] "END";
            "IF" LOW = N "THEN" N:= N1 "ELSE"
            "BEGIN" DN:= D[N]; DELTA:= D[N1] - DN;
                BBN1:= BB[N1];
                "IF" ABS(DELTA) < MACHTOL "THEN" R:= SQRT(BBN1) "ELSE"
                "BEGIN"
                    F:= 2 / DELTA; NUM:= BBN1 * F;
                    R:= -NUM / (SQRT(NUM * F + 1) + 1)
                "END";
                "IF" LOW = N1 "THEN"
                "BEGIN" D[N]:= DN + R; D[N1]:= D[N1] - R; N:= N - 2
                "END"
                "ELSE"
                "BEGIN" COUNT:= COUNT + 1;
                    "IF" COUNT > MAX "THEN" "GOTO" END;
                    "IF" LOW < OLDLOW "THEN"
                    "BEGIN" SHIFT:= 0; OLDLOW:= LOW "END"
                    "ELSE"  SHIFT:= DN + R;
                    H:= D[LOW] - SHIFT;
                    "IF" ABS(H) < MACHTOL "THEN" H:= "IF" H <= 0 "THEN"
                    -MACHTOL "ELSE" MACHTOL;
                    G:= H; T:= G * H;
                    BBI:= BB[LOW]; P:= T + BBI; I1:= LOW;
                    "FOR" I:= LOW + 1 "STEP" 1 "UNTIL" N "DO"
                    "BEGIN" S:= BBI / P; C:= T / P;
                        H:= D[I] - SHIFT - BBI / H;
                        "IF" ABS(H) < MACHTOL "THEN" H:= "IF" H <= 0
                        "THEN" -MACHTOL "ELSE" MACHTOL;
                        OLDG:= G; G:= H * C; T:= G * H;
                        D[I1]:= OLDG - G + D[I];
                        BBI:= "IF" I = N "THEN" 0 "ELSE" BB[I];
                        P:= T + BBI; BB[I1]:= S * P; I1:= I
                    "END";
                    D[N]:= G + SHIFT
                "END" QRSTEP
            "END"
        "END";
     END: EM[3]:= SQRT(BBMAX); EM[5]:= COUNT; QRIVALSYMTRI:= N
    "END" QRIVALSYMTRI

         "EOP"