DO WHILE nextid>0
            SEEK nextid
            IF newx=>x THEN 
                IF newy=>y THEN 
                    nextid=bxby
                    IF EMPTY(nextid) THEN 
                        REPLACE bxby WITH i
                    ENDIF 
                ELSE 
                    nextid=bxsy
                    IF EMPTY(nextid) THEN 
                        REPLACE bxsy WITH i
                    ENDIF 
                ENDIF 
            ELSE 
                IF newy=>y THEN 
                    nextid=sxby
                    IF EMPTY(nextid) THEN 
                        REPLACE sxby WITH i
                    ENDIF 
                ELSE 
                    nextid=sxsy
                    IF EMPTY(nextid) THEN 
                        REPLACE sxsy WITH i
                    ENDIF 
                ENDIF 
            ENDIF 
        ENDDO 

выбираем сектор по x и по y
    SELECT * ;
        FROM points ;
        WHERE (sectorx=fromxsector) AND (sectory=fromysector) ;
        INTO CURSOR fromsector READWRITE 
    IF EMPTY(i_square) THEN 
        i_square=1
    ENDIF 
выбираем квадратик вокруг заданной точки, так, чтобы в него попало от 0 до 100 точек
    done=.f.
    DO WHILE not done
        SELECT * ;
            FROM fromsector ;
            WHERE (fromx-i_square<=x) AND (x<=fromx+i_square) ;
                AND (fromy-i_square<=y) AND (y<=fromy+i_square) ;
            INTO CURSOR selpoint
        selpcnt=RECCOUNT('selpoint')
        DO CASE 
        CASE selpcnt=0
            i_square=i_square*1.9
        CASE selpcnt>100
            i_square=i_square/2.1
        otherwise 
            done=.t.
        ENDCASE 
    ENDDO 
считаем расстояния до выбранных точек
    find_dist=distance(i_square,i_square)
    find_id=0
    SELECT selpoint
    SCAN
        i_dist=distance(fromx,fromy,x,y)
        IF find_dist>i_dist THEN 
            find_dist=i_dist
            find_id=id
        ENDIF 
    SELECT selpoint
    ENDSCAN 

ACOS(SIN(fromy)*SIN(y)+COS(fromy)*COS(y)*COS(x-fromx))