Re: beginner’s question with Maxi ma

The definition of $sum, in source file asum.lisp is set up so that it does
not evaluate its arguments universally.
This makes sense since  sum(f(i),i,a,b)  should conventionally not evaluate
i, or f(i) -- until it is examined somewhat,
 but should evaluate a and b.

Here's the definition in Maxima. It calls dosum to do the real work. Dosum
and its subroutines are responsible for a lot of effort.

(defmspec $sum (l)
  (arg-count-check 4 l)
  (setq l (cdr l))
  (dosum (car l) (cadr l) (meval (caddr l)) (meval (cadddr l)) t
:evaluate-summand t))

If you want to put the first argument of a sum-like function at the end, so
you say  rsum(i,1,n,f(i)),  then here's
a definition  for a reversed sum, rsum.  [this ancient code is using
original lisp names:  (car '(a b c d)) is a.  (cadddr '(a b c d)) is d.]

(defmspec $rsum (l)
  (arg-count-check 4 l)
  (setq l (cdr l))
(dosum (cadddr l)   (car l) (meval (cadr l)) (meval (caddr l)) t
:evaluate-summand t))

Of course humans are very flexible and in most circumstances I would think
that
learning to use sum() should not be much of a burden.

RJF

On Sat, Aug 22, 2026 at 4:56 PM Stavros Macrakis <[email protected]> wrote:

> I suspect that your macro problem is because of the peculiar behavior of
> *sum*, but I haven't been able to track it down yet. Stay tuned.
>
>
> On Sat, Aug 22, 2026, 17:39 <[email protected]> wrote:
>
>> > There are two separable parts to your computation.
>> > 1. The syntax hacking
>> > 2. The computation
>>
>> True enough. At the moment, my interpretation of how the ::= operator
>> would work seems to have been faulty.
>>
>> > Good luck.
>>
>> Thank you for your advice and your well wishes.
>>
>>
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