Math functions in LISP

[cadsterdyne]

Hi Forum.

 

By general math calculation on calculator this expression

40 + (20 * 1/60) + (50 * 1/60 * 1/60) = 40.34722222

 

here is the same thing i am trying to do in auto cad command line.

 

(+ 40 (+ (* 20 (/ 1 60)) (* 50(* (/ 1 60 ) (/ 1 60)))))

and it returns 40 as the answer am i missing something.

[rlx]

Yes your missing something :-)

 

 

since you only use integers , lisp will only return integers. Try using (/ 1.0 60) or (/ 1 60) and see what happens

 

 

gr. Rlx

[MURAl_KMD]

hi

Have a look

(+ 40 (+ (* 20 (/ 1.0 60)) (* 50(* (/ 1.0 60 ) (/ 1.0 60)))))
(rtos (+ 40 (+ (* 20 (/ 1.0 60)) (* 50(* (/ 1.0 60 ) (/ 1.0 60))))) 2)

[BIGAL]

my go

 

(setq 60th (/ 1.0 60.0))
(+ 40.0 (+ (* 20.0 60th) (* 50.0 (* 60th 60th))))

[cadsterdyne]

Aa Haaa...!!!

I read that, now i remember..... Thanks a lot rlx and MURAl_KMD...

 

Autolisp Noob alert...!

[cadsterdyne]

Thanks BIGAL that looks like some advanced level AutoLisping

[Bill Tillman]

The above advice is spot on. I use many large programs and in an attempt to save kilobytes, and typing I use

(+ 40. (+ (* 20. (/ 1 60.)) (* 50. (* (/ 1. 60 ) (/ 1. 60)))))

Not too much savings and these days, HD space and memory runs in the Gigabytes, but it's just been my style. This only works if your numbers are whole. Also, I've found that you can omit the .0 on some of the numbers. As long as at least one of them has a decimal point LISP will perform floating point arithmetic on the equation for you.