code 34436;
boolean procedure ZEROINRAT(X, Y, FX, TOLX);
real X, Y, FX, TOLX;
begin integer EXT; boolean FIRST;
        real B, FB, A, FA, D, FD, C, FC, FDB, FDA, W,
        MB, TOL, M, P, Q, DW;
        DW:= DWARF; B:= X; FB:= FX; A:= X:= Y; FA:= FX; FIRST:= true;
    INTERPOLATE: C:= A; FC:= FA; EXT:= 0;
    EXTRAPOLATE: if ABS(FC) < ABS(FB) then 
        begin if C ^= A then begin D:= A; FD:= FA end;
            A:= B; FA:= FB; B:= X:= C; FB:= FC; C:= A; FC:= FA
        end INTERCHANGE;
        TOL:= TOLX; M:= (C + B) * .5; MB:= M - B;
        if ABS(MB) > TOL then 
        begin if EXT > 3 then W:= MB else 
            begin TOL:= TOL * SIGN(MB);
                P:= (B - A) * FB; if FIRST then 
                begin Q:= FA - FB; FIRST:= false end else 
                begin FDB:= (FD - FB) / (D - B);
                    FDA:= (FD - FA) / (D - A);
                    P:= FDA * P; Q:= FDB * FA - FDA * FB
                end; if P < 0 then 
                begin P:= -P; Q:= -Q end;
                if EXT = 3 then P:= P * 2;
                W:= if P < DW or P <= Q * TOL then TOL else 
                if P < MB * Q then P / Q else MB
            end; D:= A; FD:= FA; A:= B; FA:= FB;
            X:= B:= B + W; FB:= FX;
            if (if FC >= 0 then FB >= 0 else FB <= 0) then 
            goto INTERPOLATE else 
            begin EXT:= if W = MB then 0 else EXT + 1;
                goto EXTRAPOLATE
            end 
        end; Y:= C;
        ZEROINRAT:= if FC >= 0 then FB <= 0 else FB >= 0
end ZEROINRAT;
        eop