Re: [Maxima-discuss] modest calculation that calls infsimp 2.4 million times

[Barton W. <wi...@un...>]

(%i2) timer(?simpprod);
(%o2) [simpprod]
(%i3) xxx : product(f(i),i,1,inf)$
(%i4) xxx : subst(f(i) = product(g(k),k,1,inf), xxx)$
(%i5) timer_info();
(%o5) matrix(
            [function,  time\/call, calls,      runtime,    gctime],
            [simpprod,  1.4972326095270472*10^-4*sec, 47066,      7.046875*sec,     0],
            [total,     1.4972326095270472*10^-4*sec, 47066,      7.046875*sec,     0]  )

Over 47,000 calls to simpprod is crazy.  Let's try this again, but define infsimp to be the identity fumction:


(%i1) timer(?simpprod);
(%o1) [simpprod]
(%i2) :lisp(defun infsimp (e) e);
INFSIMP
(%i2) xxx : product(f(i),i,1,inf)$
(%i3) xxx : subst(f(i) = product(g(k),k,1,inf), xxx)$
(%i4) timer_info();
(%o4) matrix(
            [function,  time\/call, calls,      runtime,    gctime],
            [simpprod,  4.222972972972973*10^-4*sec,  74,   0.03125*sec,      0],
            [total,     4.222972972972973*10^-4*sec,  74,   0.03125*sec,      0]
      )

Now only 74 calls to simpprod—that's too many, I think, but it's better than 47,000.
________________________________
From: Barton Willis via Maxima-discuss <max...@li...>
Sent: Monday, October 20, 2025 9:21 AM
To: <max...@li...> <max...@li...>
Subject: [Maxima-discuss] modest calculation that calls infsimp 2.4 million times

Caution: Non-NU Email

If you all are looking for a puzzle that is possibly more fun than Sudoko or Queens, figure out why infsimp is called over 2.4 million times to do the following modest calculation:

(%i1) timer(?infsimp)$

(%i2) xxx : product(f(i),i,1,inf)$

(%i3) xxx : subst(f(i) = product(g(k),k,1,inf), xxx)$

(%i4) xxx : subst(g(k) = product(w(m),m,1,inf), xxx)$

(%i5) timer_info();
(%o5) matrix(
            [function,  time\/call, calls,      runtime,    gctime],
            [infsimp,   6.329070747905959*10^-5*sec,  2400382,    151.921875*sec,   0],
            [total,     6.329070747905959*10^-5*sec,  2400382,    151.921875*sec,   0]
      )

I haven't tried to figure this out.

--Barton