Peter Poeliejoe
04-12-10  17:21



When I type this (AutoLISP):

(+ 10000.8 2.4), the result is 10003.2, as expected.


However, when typed: (+ 100000.8 2.4), the result is

100003.0.
Is 100000 a magical border voor a real in AutoLISP? Any settings involved here?


Thanks in advance for any brain activity...Peter

All I can say is the system isn't perfect. LISP is a very old language and relied upon many many different factors that probably aren't in place with any of today's technology.Good Luck!!

Lisp is limited by the same precision as is AutoCAD. It can store 16 digits in a number. To properly display numbers as internally calculated, use the "rtos" function.
 
For your example, you'll see the accurate decimals by setting precision to 1 or higher:
(rtos (+ 100000.0 3.2) 2 1)
 
where the "2" specifies decimal output, "1" is the precision, which can be 0 to 16.
 
With large numbers, the number of decimal places may be less that the precision; such as:
Command: (rtos 1234567890.0987654321 2 16)"1234567890.098765"
 

Nice!! Thanks Carl. I guess I learned my 'something new' today. I have a limited knowledge of LISP, but I do have a background in computer programming and love getting tidbits of info like this.

CarlB,
 
thanks for your answer.
I think this is exactly the information I was looking for.
 
Peter