Re: [Maxima-discuss] Maxima functions for plusp, timesp, and exptp in src?

[Stavros M. <mac...@al...>]

What is the motivation for these functions? Is it to make life easier for
beginners? I think it's a false simplicity. All in all, I think it's
generally better for users who want to manipulate expressions
programmatically to stick with *inflag=true*, for exactly the reasons that
Maxima uses its internal representation: simplicity and consistency. *part* is
good for interactive use, but a mess for programmatic manipulation.

Details:

   - You also need *quotientp *and (unary) *minusp *(assuming you're not
   binding *inflag* to *true*)
   - What do you want *minusp* to do for negative numbers? They are
      *mapatom*s, but have part/0 = "-" (but part/0 is an error with
      *inflag=true*)
      - What do you want *quotientp* to do for rational numbers? They are
      *mapatom*s, but have part/0 = "/" (regardless of *inflag*).
   - If you really want to be consistent with *part* (which is arguably
   helpful for naive users):
      -  you'll also need *sqrtp *(unless you bind *sqrtdispflag* to *false*
      )
      - Note that even with *inpart=false*, *part *is not fully consistent
      with the displayed form:  *op(a-b)* is "+", not "-"
      - Oh, and the order of *args(x-y) *depends on *negsumdispflag*.
      - Users still need to understand *mapatom* for cases like
   *op(ex)='sin*
   - The functions' behavior depends on the global setting of *inflag *and
   *%edispflag *-- is that your intent?
   - They modify the global value of *piece *-- that means that mixing them
   with *part* is problematic

            -s



On Sun, Jul 31, 2022 at 2:32 PM Barton Willis via Maxima-discuss <
max...@li...> wrote:

> Would these functions be worthy additions to /src?
>
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> (defmfun $timesp (x) (and (not ($mapatom x)) (equal ($part x 0) "*")))
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>
> (defmfun $plusp  (x) (and (not ($mapatom x)) (equal ($part x 0) "+")))
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> (defmfun $exptp  (x) (and (not ($mapatom x)) (equal ($part x 0) "^")))
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> Or should they be defined differently?  I think we’ve talked about this
> before.
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> Instead of ($part x 0), we could call mpart.
>
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> --Barton
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