"CODE" 33018 ;
   "PROCEDURE" RK5NA(X, XA, B, FXJ, J, E, D, FI, N, L, POS);
   "VALUE" FI, N, L, POS; "INTEGER" J, N, L; "BOOLEAN" FI, POS;
   "REAL" B, FXJ; "ARRAY" X, XA, E, D;
   "BEGIN" "INTEGER" I;
      "BOOLEAN" FIRST, FIR, REJ;
      "REAL" FHM, S, S0, COND0, S1, COND1, H, ABSH, TOL, FH,
      HL, MU, MU1;
      "ARRAY" Y, XL, DISCR[0:N], K[0:5,0:N], E1[1:2];
      "REAL" "PROCEDURE" SUM(J,A,B,XJ) ; "INTEGER" J,A,B ; "REAL" XJ ;
      "BEGIN" "REAL" S ; S:= 0 ;
         "FOR" J:=A "STEP" 1 "UNTIL" B "DO" S:=S+XJ ; SUM:= S
      "END" SUM ;
      "PROCEDURE" RKSTEP(H, D); "VALUE" H, D; "INTEGER" D; "REAL" H;
      "BEGIN" "INTEGER" I;
         "PROCEDURE" F(T); "VALUE" T; "INTEGER" T;
         "BEGIN" "INTEGER" I;
            "REAL" P;
            "FOR" J:= 0 "STEP" 1 "UNTIL" N "DO" Y[J]:= FXJ;
            P:= H / SQRT(SUM(I, 0, N, Y[I] ** 2));
            "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" K[T,I]:= Y[I] * P
         "END" F;
         "IF" D = 2 "THEN" "GOTO" INTEGRATE; "IF" D = 1 "THEN"
         "BEGIN" "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" K[0,I]:= K[0,I]
            * MU; "GOTO" A
         "END";
         "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I]; F(0);
      A: "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I] +
         K[0,I] / 4.5; F(1);
         "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I] + (K[0,I]
         + K[1,I] * 3) / 12; F(2);
         "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I] + (K[0,I]
         + K[2,I] * 3) / 8; F(3);
         "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I] + (K[0,I]
         * 53 - K[1,I] * 135 + K[2,I] * 126 + K[3,I] * 56)
         / 125; F(4); "IF" D <= 1 "THEN"
         "BEGIN" "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I] +
            (K[0,I] * 133 - K[1,I] * 378 + K[2,I] * 276 +
            K[3,I] * 112 + K[4,I] * 25) / 168; F(5);
            "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" DISCR[I]:=
            ABS(K[0,I] * 21 - K[2,I] * 162 + K[3,I] * 224
            - K[4,I] * 125 + K[5,I] * 42) / 14; "GOTO" END
         "END";
      INTEGRATE: "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I]
         + ( - K[0,I] * 63 + K[1,I] * 189 - K[2,I] * 36 -
         K[3,I] * 112 + K[4,I] * 50) / 28; F(5);
         "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I] + (K[0,I]
         * 35 + K[2,I] * 162 + K[4,I] * 125 + K[5,I] * 14)
         / 336;
      END:
      "REAL" "PROCEDURE" FZERO;
      "BEGIN" "IF" S = S0 "THEN" FZERO:= COND0 "ELSE" "IF" S = S1
         "THEN" FZERO:= COND1 "ELSE"
         "BEGIN" RKSTEP(S - S0, 3); FZERO:= B "END"
      "END" FZERO;

      "IF" FI "THEN"
      "BEGIN" "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" D[I + 3]:= XA[I];
         D[1]:= D[2]:= 0
      "END";
      "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" X[I]:= XL[I]:= D[I + 3];
      S:= D[1]; FIRST:= FIR:= "TRUE"; H:= E[0] + E[1];
      "FOR" I:= 1 "STEP" 1 "UNTIL" N "DO"
      "BEGIN" ABSH:= E[2 * I] + E[2 * I + 1];
         "IF" H > ABSH "THEN" H:= ABSH
      "END";
      "IF" FI "THEN"
      "BEGIN" J:= L; "IF" FXJ * H < 0 "EQV" POS "THEN" H:= - H "END"
      "ELSE" "IF" D[2] * H < 0 "THEN" H:= - H; I:= 0;
   AGAIN: RKSTEP(H, I); REJ:= "FALSE"; FHM:= 0;
      ABSH:= ABS(H);
      "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO"
      "BEGIN" TOL:= E[2 * I] * ABS(K[0,I]) + E[2 * I + 1] *
         ABSH; REJ:= TOL < DISCR[I] "OR" REJ;
         FH:= DISCR[I] / TOL; "IF" FH > FHM "THEN" FHM:= FH
      "END";
      MU:= 1 / (1 + FHM) + .45; "IF" REJ "THEN"
      "BEGIN" H:= H * MU; I:= 1; "GOTO" AGAIN "END";
      "IF" FIRST "THEN"
      "BEGIN" FIRST:= FIR; HL:= H; H:= MU * H "END"
      "ELSE"
      "BEGIN" FH:= MU * H / HL + MU - MU1; HL:= H; H:= FH * H
      "END";
   ACCEPT: RKSTEP(HL, 2); MU1:= MU; S:= S + HL;
      "IF" FIR "THEN"
      "BEGIN" COND0:= B; FIR:= "FALSE"; "IF" "NOT"FI "THEN" H:= D[2]
      "END"
      "ELSE"
      "BEGIN" D[2]:= H; COND1:= B;
         "IF" COND0 * COND1 <= 0 "THEN" "GOTO" ZERO;
         COND0:= COND1
      "END";
      "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" D[I + 3]:= XL[I]:= X[I];
      D[1]:= S0:= S; I:= 0; "GOTO" AGAIN;
   ZERO: E1[1]:= E[2 * N + 2]; E1[2]:= E[2 * N + 3];
      S1:=S ; S:=S0 ;
      ZEROIN(S,S1,FZERO,ABS(E1[1]*S)+ABS(E1[2])) ;
      RKSTEP(S - S0, 3);
      "FOR" I:= 0 "STEP" 1 "UNTIL" N "DO" D[I + 3]:= X[I]; D[1]:= S
   "END" RK5NA;
        "EOP"