[sage-devel] Re: Changes in Maxima behavior
Just as a followup. It appears to me that ...
radcan() should not consult the setting of domain, so far as I can tell,
except
in the situation in which it produces a result and then runs it through
simplifya
the main simplification program.
That program apparently un-does the simplification that radcan produces,
and so radcan notices the persistence of a radical that it can simplify, and
does so again. And again. I'm not sure what to say about this being a bug.
Is it a user error to specify domain:complex? Should radcan bind domain
to real (note: when radcan was written, domain setting did not exist)
in which case the radcan program is secretly unsetting a user option? Maybe
that's the thing to do, Robert...
The occurrence of *alpha is some trace is related to using
a modular polynomial GCD algorithm. See the source code at rat3c.lisp,
where you see that this number is chosen as the modulus; a positive prime
sort of near
the (positive :) square root of the largest fixnum in (some) lisp.
My guess is that it is computing a GCD of v^2+u^2-1 and its derivative
with respect to u or v to see if it is a perfect square, in which case
maybe it can be taken outside the square root.
On Tuesday, July 2, 2013 9:53:19 AM UTC-7, Robert Dodier wrote:
On 2013-07-01, Joris Vankerschaver joris.van...@gmail.com javascript:
wrote:
sage: u, v = var('u, v', domain='real')
sage: sqrt(-1/(u^2+v^2-1)).simplify_radical() # This will hang
This is a bug in Maxima:
(%i2) radcan (sqrt (-1 / (u^2 + v^2 - 1))), domain=complex;
It waits apparently forever here -- but it is actually looping over
*ALPHA (not sure why) which is a large prime number (8388593).
(%i3) :lisp (setq *alpha 17)
17
(%i3) radcan(sqrt(-1/(u^2+v^2-1))), domain=complex;
(%o3) 1/sqrt(-v^2-u^2+1)
I've reported this as bug # 2605.
best
Robert Dodier
--
You received this message because you are subscribed to the Google Groups
sage-devel group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/groups/opt_out.
[sage-devel] Re: Changes in Maxima behavior
On Friday, June 28, 2013 11:14:55 AM UTC-4, rjf wrote: On Friday, June 28, 2013 5:09:49 AM UTC-7, Joris Vankerschaver wrote: Hi all, Is there something I can do to avoid this? I tried this in Maxima 5.25.1 and 5.28.02 You can avoid this problem by just using one of those versions of Maxima directly. I suspect, but do not know, that simplify_full is just a call to fullratsimp() in Maxima. Just as a point of information, it calls this as well as a number of other simplifications in Maxima. -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/groups/opt_out.
[sage-devel] Re: Changes in Maxima behavior
On 2013-07-01, Joris Vankerschaver joris.vankerscha...@gmail.com wrote:
sage: u, v = var('u, v', domain='real')
sage: sqrt(-1/(u^2+v^2-1)).simplify_radical() # This will hang
This is a bug in Maxima:
(%i2) radcan (sqrt (-1 / (u^2 + v^2 - 1))), domain=complex;
It waits apparently forever here -- but it is actually looping over
*ALPHA (not sure why) which is a large prime number (8388593).
(%i3) :lisp (setq *alpha 17)
17
(%i3) radcan(sqrt(-1/(u^2+v^2-1))), domain=complex;
(%o3) 1/sqrt(-v^2-u^2+1)
I've reported this as bug # 2605.
best
Robert Dodier
--
You received this message because you are subscribed to the Google Groups
sage-devel group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/groups/opt_out.
[sage-devel] Re: Changes in Maxima behavior
Hi all,
Following RJF's suggestion, I played around with Maxima for a little while
to see where the problem arises. As far as I can tell, this is again a
problem with the fact that simplify_radical gets called in simplify_full
(see #12737). The problem that I'm seeing used to be absent when
simplify_radical still set the domain to 'real' before invoking radcan, but
now that it no longer does that, the problem has become apparent, see below.
First of all, I simplified the example in the original post to
sage: u, v = var('u, v', domain='real')
sage: sqrt(-1/(u^2+v^2-1)).simplify_radical() # This will hang
The problem is with the fact that the domain of the symbolic variables is
complex:
sage: maxima.interact()
maxima: forget()
[]
maxima: domain
complex
maxima: assume(x 0)
[x0]
maxima: assume(y 0)
[y0]
maxima: radcan(sqrt(-1/(x^2 + y^2 - 1)))
Setting the domain to 'real' fixes the problem:
sage: maxima.interact()
maxima: domain: real
real
maxima: radcan(sqrt(-1/(x^2 + y^2 - 1)))
%i/sqrt(y^2+x^2-1)
The upshot seems to be that this is not really a bug, but again an annoying
consequence of simplify_radical not really being a simplify_ method, and
this should be fixed once #11912 and #12737 are approved. Therefore I won't
open a new ticket, but I'll just add to the discussion of those patches.
All the best,
Joris
On Friday, June 28, 2013 1:09:49 PM UTC+1, Joris Vankerschaver wrote:
Hi all,
I've been out of the Sage loop for a while, but upon upgrading to 5.10, I
found that Maxima seems to choke on the following innocuous code which used
to run fine. I'm posting this here, because this issue came up while I was
working on #10132, and also because it affects usability.
sage: u, v = var('u,v')
sage: assume(u, 'real')
sage: assume(v, 'real')
sage: assume(u^2 + v^2 1)
sage: n = vector((u/sqrt(-u^2 - v^2 + 1), v/sqrt(-u^2 - v^2 + 1), 1))
sage: norm = n.norm(); norm
sqrt(abs(u/sqrt(-u^2 - v^2 + 1))^2 + abs(v/sqrt(-u^2 - v^2 + 1))^2 + 1)
sage: norm.simplify_full()
The last command just sits there on 5.10, and consumes all the resources
(more specifically, /Users/Joris/sage/local/bin/sage-cleaner consumes all
the available memory). In Sage 5.3, the last command just would return
I/sqrt(u^2 + v^2 - 1) which is not very nice but at least it's short and
fast.
Is this known? Is there something I can do to avoid this?
All the best,
Joris
--
You received this message because you are subscribed to the Google Groups
sage-devel group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/groups/opt_out.
[sage-devel] Re: Changes in Maxima behavior
I can confirm the regression, after a few seconds I get
TypeError: ECL says: Memory limit reached. Please jump to an outer pointer,
quit program and enlarge the
memory limits before executing the program again.
The process that consumes the memory is sage-ipython (in the ECL shared
library), not sage-cleaner.
On Friday, June 28, 2013 8:09:49 AM UTC-4, Joris Vankerschaver wrote:
Hi all,
I've been out of the Sage loop for a while, but upon upgrading to 5.10, I
found that Maxima seems to choke on the following innocuous code which used
to run fine. I'm posting this here, because this issue came up while I was
working on #10132, and also because it affects usability.
sage: u, v = var('u,v')
sage: assume(u, 'real')
sage: assume(v, 'real')
sage: assume(u^2 + v^2 1)
sage: n = vector((u/sqrt(-u^2 - v^2 + 1), v/sqrt(-u^2 - v^2 + 1), 1))
sage: norm = n.norm(); norm
sqrt(abs(u/sqrt(-u^2 - v^2 + 1))^2 + abs(v/sqrt(-u^2 - v^2 + 1))^2 + 1)
sage: norm.simplify_full()
The last command just sits there on 5.10, and consumes all the resources
(more specifically, /Users/Joris/sage/local/bin/sage-cleaner consumes all
the available memory). In Sage 5.3, the last command just would return
I/sqrt(u^2 + v^2 - 1) which is not very nice but at least it's short and
fast.
Is this known? Is there something I can do to avoid this?
All the best,
Joris
--
You received this message because you are subscribed to the Google Groups
sage-devel group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/groups/opt_out.
[sage-devel] Re: Changes in Maxima behavior
On Friday, June 28, 2013 5:09:49 AM UTC-7, Joris Vankerschaver wrote: Hi all, Is there something I can do to avoid this? I tried this in Maxima 5.25.1 and 5.28.02 You can avoid this problem by just using one of those versions of Maxima directly. I suspect, but do not know, that simplify_full is just a call to fullratsimp() in Maxima. -- You received this message because you are subscribed to the Google Groups sage-devel group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/groups/opt_out.
