Routine is flakey, why?

Group,
I have a routine, see below. It is called linelength and is used to select
lines of a certain length. I seems to work with either longer lines, or of a
length of a whole number. For example it will find all 1'' lines but will
not find lines of say 89/259". I have worked with units and precision but no
luck.

Here it is, any ideas?
Thanks!

(defun c:linelength()
(if (not asked-length)(setq asked-length 660.0)) ; just a length
(setq answer-asked-length (getreal (strcat "Enter length <" (rtos
asked-length) ">:")))
(if answer-asked-length (setq asked-length answer-asked-length))
(setq tolerance 1e-12)
(setq entity-list nil)
(setq entity-list (ssadd)) ; create new, empty selection set

(setq teller 0)
(setq entlyst (ssget "X")) ; select every thing in the drawing
(setq entlystl (sslength entlyst))

(while (< teller entlystl) ; test through all entities
(setq entityname (ssname entlyst teller))
(setq entdatalyst (entget(ssname entlyst teller)))
(setq enttype (cdr(assoc 0 entdatalyst)))

(if (= enttype "LINE") ; test if entity is a line
(progn

(setq assoc10 (assoc 10 entdatalyst))
(setq p10 (cdr assoc10)) ; WCS coordinates
(setq p10 (trans p10 0 1)) ; UCS coordinates

(setq assoc11 (assoc 11 entdatalyst))
(setq p11 (cdr assoc11)) ; WCS coordinates
(setq p11 (trans p11 0 1)) ; UCS coordinates

(setq line-length (distance p10 p11))

(if (< (abs(- line-length asked-length))tolerance) ; test length of line
(setq entity-list (ssadd entityname entity-list))
)

);progn
);if

(setq teller (+ 1 teller))
);while

(setq set entity-list) ; short name for the set of selected objects
(princ (sslength set))(princ " lines selected")(princ)
(princ ", Call this set in responce to 'select objects' with: !set")(princ)
);defun

(princ "\nStart command: linelength")(princ)

 

I think this statement is causing the flaky results...

line

I think it's the same thing roughly as...

(if
(equal line-length asked-length tolerance)
...
)

The tolerance value argument in the equal function is the degree of variance
allowed to still result as equal when the line-length and asked-length are
compared.

But I think the (abs) is causing problems. So try the (equal) and let me
know if it does what it is that you want. If I'm going to help further
though, then you will need to tell me the logic that your program uses to
accept line lengths into your selection set. I'm not sure but I think your
logic is flawed in the top statement above.

HTH,

Devin

 

That took care of it, thank you very much!
TEW