"CODE" 34423;
  "PROCEDURE" DECTRI(SUB, DIAG, SUPER, N, AUX);
  "VALUE" N; "INTEGER" N; "ARRAY" SUB, DIAG, SUPER, AUX;
  "BEGIN" "INTEGER" I, N1;
     "REAL" D, R, S, U, NORM, NORM1, TOL;
     TOL:= AUX[2]; D:= DIAG[1]; R:= SUPER[1];
     NORM:= NORM1:= ABS(D) + ABS(R);
     "IF" ABS(D) <= NORM1 * TOL "THEN"
     "BEGIN" AUX[3]:= 0; AUX[5]:= D; "GOTO" EXIT "END";
     U:= SUPER[1]:= R / D; S:= SUB[1]; N1:= N - 1;
     "FOR" I:= 2 "STEP" 1 "UNTIL" N1 "DO"
     "BEGIN" D:= DIAG[I]; R:= SUPER[I];
        NORM1:= ABS(S) + ABS(D) + ABS(R);
        D:= DIAG[I]:= D - U * S;
        "IF" ABS(D) <= NORM1 * TOL "THEN"
        "BEGIN" AUX[3]:= I - 1; AUX[5]:= D; "GOTO" EXIT "END";
        U:= SUPER[I]:= R / D; S:= SUB[I];
        "IF" NORM1 > NORM "THEN" NORM:= NORM1
     "END";
     D:= DIAG[N]; NORM1:= ABS(D) + ABS(S);
     D:= DIAG[N]:= D - U * S;
     "IF" ABS(D) <= NORM1 * TOL "THEN"
     "BEGIN" AUX[3]:= N1; AUX[5]:= D; "GOTO" EXIT "END";
     "IF" NORM1 > NORM "THEN" NORM:= NORM1;
     AUX[3]:= N; AUX[5]:= NORM;
 EXIT:
 "END" DECTRI

        "EOP"