Hi all...

Long time no challenges asked... This one is really tough and I think that IMHO is still impossible to be solved...

Now to get to the point. Through long period of time I coded in ALISP and very often I came into situation where I have to use math or some programming skills to write and translate real formula or pseudo code to ALISP defined function either by using (defun), (lambda) - defun-q I use rarely... Now if you take this simple formula A=B+3 and you translate it into this :

(defun a ( b )

(+ b 3)

)

Result of (a 2) would be 5... That's fine... But what if formula is very complex and not so evident and you still have USUBR a which will operate the same (a 2) => 5... Now the goal of this challenge is to get USUBR ainv which will give (ainv 5) => 2 ...

So you have defined function - it could be as simple as (chr 65) => "A" ... Now we need to get (ascii) function from (chr), so that (chrinv "A") => 65 - the same as (ascii "A") => 65...

Let's see if some eminent person like Lee Mac, or MP can do it... For a start I am narrowing things to only pure math and math formula where you define function with 1 number argument and 1 return as number and the goal is to get inverse function also with 1 number argument and 1 return as number...

Thanks for reply in advance...

Regards, M.R.