Re: Elisp function that performs numeric computations

[Manuel Giraud]

fatiparty--- via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org> writes:

> Jan 19, 2022, 19:20 by help-gnu-emacs@gnu.org:
>
>>
>> I would like to construct an elisp function that performs numeric
>> computations and outputs the result.
>>
>> j = rptdepth
>> w = maxdepth - j
>> p = w + 1
>>
>> output = j + ( (depth - maxdepth - 1) mod p )
>>
> I have done as follows.  But one problem is: How do I use the output
> in another elisp function?
>
> (defun test (depth maxdepth rptdepth)
>   "Compute depth to use."
>   (interactive)
>   
>   (let* ( (j rptdepth)
>           (w (- maxdepth j))
>           (p (+ w 1))
>           (r (mod (- depth maxdepth 1) p) )
>           (o (+ j r)) )
>
>     (message "usedepth: %d" o) ))

Hi,

A `let' form returns the value of the last expression of its body. In
your function, it is "(message…)" which returns the string of the
message. If you want your function to return `o' just append it as the
last expression:

(defun test (depth maxdepth rptdepth)
  "Compute depth to use."
  (interactive)
  (let* ( (j rptdepth)
          (w (- maxdepth j))
          (p (+ w 1))
          (r (mod (- depth maxdepth 1) p) )
          (o (+ j r)))
    (message "usedepth: %d" o)
    o))

Then, you can use `test' directly:

(* (test 8 1000 9) (test 8 1000 9))
-- 
Manuel Giraud