"CODE" 35056;
"PROCEDURE" BACKWARD(X,P,Q,I0,NMAX,EPS,I);
"VALUE" X,P,Q,I0,NMAX,EPS; "INTEGER" NMAX; "REAL" X,P,Q,I0,EPS;
"ARRAY" I;
"BEGIN" "INTEGER" M,N,NU; "REAL" R,PQ,Y,LOGX;
    "ARRAY" IAPPROX[0:NMAX];
    I[0]:= I0; "IF" NMAX>0 "THEN"
    "BEGIN""FOR" N:= 1 "STEP" 1 "UNTIL" NMAX "DO" IAPPROX[N]:= 0;
        PQ:= P+Q-1; LOGX:= LN(X);
        R:= NMAX+(LN(EPS)+Q*LN(NMAX))/LOGX;
        NU:= ENTIER(R-Q*LN(R)/LOGX);
L1:     N:= NU; R:= X;
L2:     Y:= (N+PQ)*X; R:= Y/(Y+(N+P)*(1-R));
        "IF" N<= NMAX "THEN" I[N]:= R; N:= N-1;
        "IF" N >= 1 "THEN" "GOTO" L2; R:= I0;
        "FOR" N:= 1 "STEP" 1 "UNTIL" NMAX "DO" R:= I[N]:= I[N]*R;
        "FOR" N:= 1 "STEP" 1 "UNTIL" NMAX "DO"
        "IF" ABS((I[N]-IAPPROX[N])/I[N]) > EPS "THEN"
        "BEGIN" "FOR" M:= 1 "STEP" 1 "UNTIL" NMAX "DO"
            IAPPROX[M]:= I[M]; NU:= NU+5; "GOTO" L1
        "END"
    "END"
"END" BACKWARD;
        "EOP"