[sage-support] Simplifying expression, 'x' vs. 'y'
# Define
var('y'); var('x')
f(x,y)= -(x*y)*exp(-(x^2 + y^2))
fdx(x,y) = derivative(f(x,y), x)
fdy(x,y) = derivative(f(x,y), y)
# Check
print f(x,y)-f(y,x)
# Compare these
print derivative(f(x,y), x).simplify_full()
print derivative(f(x,y), y).simplify_full()
This will print
0
(2*x^2 - 1)*y*e^(-x^2 - y^2)
(2*x*y^2 - x)*e^(-x^2 - y^2)
Why is this? I can add .collect('x') at end of second expression, but I
don't understand why it is not needed in first expression.
This is version 5.4.
--
Jori Mäntysalo
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[sage-support] Re: Turning off readline
On 2012-12-09, Jim Hefferon jim.heffe...@gmail.com wrote: --=_Part_14_17388356.1355069188311 Content-Type: text/plain; charset=ISO-8859-1 I am trying to turn off the command line readline action.* If that were possible, it would be a big help to me. Does anyone know? I am running Sage on a recent Ubuntu, using a recent install. I believe the readline behavior arises from pyreadline that comes in as part of ipython. I can find no documentation in ipython on how to stop readline while the repl is running (which would be ideal for me) and I tried putting in a configuration file pyreadlineconfig.ini and uncommenting its second line, but that had no effect that I could see. $ head -n2 $HOME/pyreadlineconfig.ini #Bind keys for exit (keys only work on empty lines disable_readline(True)#Disable pyreadline completely. I also had a look in the source but came away unenlightened. Thanks for any help. is pyreadline really used by Sage? It seems to be only needed on Windows, where Sage does not run. -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] Re: Installation problem
On 2012-12-10, Emmanuel emm.ro...@gmail.com wrote: --=_Part_20_25716954.1355143287028 Content-Type: text/plain; charset=ISO-8859-1 Good afternoon, Havin installed sage 5.4 on my Ubuntu distribution 12.10, I have no problem to run sage in a terminal. However, I can no more run it on my browser , apparently due to exceptions.OSError: [Errno 39] Directory not empty (see below). If I delet the .sage directory in mu user directory, then everything works fine but I have no more access to my old worksheets. Can someone suggest an idea of what is happening? Executing twistd --pidfile=sage_notebook.sagenb/sagenb.pid -ny sage_notebook.sagenb/twistedconf.tac 2012-12-10 13:30:52+0100 [-] Log opened. 2012-12-10 13:30:52+0100 [-] twistd 12.1.0 (/opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/bin/python 2.7.3) starting up. 2012-12-10 13:30:52+0100 [-] reactor class: twisted.internet.epollreactor.EPollReactor. 2012-12-10 13:30:52+0100 [-] QuietSite starting on 8081 2012-12-10 13:30:52+0100 [-] Starting factory __builtin__.QuietSite instance at 0xad4636c 2012-12-10 13:30:53+0100 [-] WSGI application error Traceback (most recent call last): File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Twisted-12.1.0-py2.7-linux-i686.egg/twisted/python/threadpool.py, you are runnig a Sage Ubunty 12.04 installation on Ubuntu 12.10. It's asking for trouble, IMHO. line 167, in _worker result = context.call(ctx, function, *args, **kwargs) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Twisted-12.1.0-py2.7-linux-i686.egg/twisted/python/context.py, line 118, in callWithContext return self.currentContext().callWithContext(ctx, func, *args, **kw) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Twisted-12.1.0-py2.7-linux-i686.egg/twisted/python/context.py, line 81, in callWithContext return func(*args,**kw) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Twisted-12.1.0-py2.7-linux-i686.egg/twisted/web/wsgi.py, line 332, in run self.reactor.callFromThread(wsgiError, self.started, *exc_info()) --- exception caught here --- File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Twisted-12.1.0-py2.7-linux-i686.egg/twisted/web/wsgi.py, line 315, in run appIterator = self.application(self.environ, self.startResponse) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Flask-0.9-py2.7.egg/flask/app.py, line 1701, in __call__ return self.wsgi_app(environ, start_response) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Flask-0.9-py2.7.egg/flask/app.py, line 1689, in wsgi_app response = self.make_response(self.handle_exception(e)) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Flask-0.9-py2.7.egg/flask/app.py, line 1687, in wsgi_app response = self.full_dispatch_request() File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Flask-0.9-py2.7.egg/flask/app.py, line 1360, in full_dispatch_request rv = self.handle_user_exception(e) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Flask-0.9-py2.7.egg/flask/app.py, line 1358, in full_dispatch_request rv = self.dispatch_request() File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/local/lib/python2.7/site-packages/Flask-0.9-py2.7.egg/flask/app.py, line 1344, in dispatch_request return self.view_functions[rule.endpoint](**req.view_args) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/devel/sagenb/flask_version/decorators.py, line 22, in wrapper return f(*args, **kwds) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/devel/sagenb/flask_version/worksheet_listing.py, line 68, in home return render_worksheet_list(request.args, pub=False, username=username) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/devel/sagenb/flask_version/worksheet_listing.py, line 43, in render_worksheet_list search=search, reverse=reverse) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/devel/sagenb/sagenb/notebook/notebook.py, line 1282, in worksheet_list_for_user X = self.get_worksheets_with_viewer(user) File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/devel/sagenb/sagenb/notebook/notebook.py, line 1460, in get_worksheets_with_viewer if self._user_manager.user_is_admin(username): return self.get_all_worksheets() File /opt/sage-5.4-linux-32bit-ubuntu_12.04.1_lts-i686-Linux/devel/sagenb/sagenb/notebook/notebook.py, line 1455, in
[sage-support] Re: Simplifying expression, 'x' vs. 'y'
On Tuesday, December 11, 2012 3:15:31 AM UTC-5, jori.ma...@uta.fi wrote:
# Define
var('y'); var('x')
f(x,y)= -(x*y)*exp(-(x^2 + y^2))
fdx(x,y) = derivative(f(x,y), x)
fdy(x,y) = derivative(f(x,y), y)
# Check
print f(x,y)-f(y,x)
# Compare these
print derivative(f(x,y), x).simplify_full()
print derivative(f(x,y), y).simplify_full()
This will print
0
(2*x^2 - 1)*y*e^(-x^2 - y^2)
(2*x*y^2 - x)*e^(-x^2 - y^2)
Partly educated guess; the Pynac print order we use
sage: fdx
(x, y) |-- 2*x^2*y*e^(-x^2 - y^2) - y*e^(-x^2 - y^2)
sage: fdy
(x, y) |-- 2*x*y^2*e^(-x^2 - y^2) - x*e^(-x^2 - y^2)
makes it easy for Maxima to guess that y*e^(-x^2-y^2) factors out of the
first expression but not the second, since the x is hidden. But this is
done in Maxima, in particular with fullratsimp
sage: fdx.simplify_rational()
(x, y) |-- (2*x^2 - 1)*y*e^(-x^2 - y^2)
sage: fdy.simplify_rational()
(x, y) |-- (2*x*y^2 - x)*e^(-x^2 - y^2)
I wouldn't worry about it, since in general there is no way to define
simpler expression that is fully useful at all times, and for more
complicated expressions more detail work would be needed anyway.
- kcrisman
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[sage-support] Re: Turning off readline
On Tuesday, December 11, 2012 7:45:10 AM UTC-5, Dima Pasechnik wrote: is pyreadline really used by Sage? It seems to be only needed on Windows, where Sage does not run. Thanks for your comment. Probably I have it wrong. I based my opinion on this from the Sage FAQ: http://wiki.sagemath.org/faq#Why_is_Sage.27s_command_history_different_than_Magma.27s buttressed by the fact that if you type garbage into the repl then Sage gives an error message that refers to the ipython console. But evidence that I am wrong is that I also see readline-6.2.p3.spkg in my /usr/local/sage/spkg/standard directory, so I could be convinced either way. Assuming that Sage uses GNU readline, I spelunked the readline manual looking for a way to disable either dynamically or at startup and did not see anything. I also have spent some time trying to influence the behavior of readline via INPUTRC, as here bash$ INPUTRC=./inputrc sage but I observed no effect (in ./inputrc I tried setting horizontal-scroll-mode=off). Could easily be my cluelessness that caused it to not work, though. Obviously I'm thrashing here, so I'm glad for any insight. -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] Re: Turning off readline
On 12/11/12 8:07 AM, Jim Hefferon wrote: On Tuesday, December 11, 2012 7:45:10 AM UTC-5, Dima Pasechnik wrote: is pyreadline really used by Sage? It seems to be only needed on Windows, where Sage does not run. Thanks for your comment. Probably I have it wrong. I based my opinion on this from the Sage FAQ: http://wiki.sagemath.org/faq#Why_is_Sage.27s_command_history_different_than_Magma.27s buttressed by the fact that if you type garbage into the repl then Sage gives an error message that refers to the ipython console. But evidence that I am wrong is that I also see readline-6.2.p3.spkg in my /usr/local/sage/spkg/standard directory, so I could be convinced either way. Assuming that Sage uses GNU readline, I spelunked the readline manual looking for a way to disable either dynamically or at startup and did not see anything. I also have spent some time trying to influence the behavior of readline via INPUTRC, as here bash$ INPUTRC=./inputrc sage but I observed no effect (in ./inputrc I tried setting horizontal-scroll-mode=off). Could easily be my cluelessness that caused it to not work, though. Obviously I'm thrashing here, so I'm glad for any insight. Sage has an expect interface for Sage: http://hg.sagemath.org/sage-main/file/33242a07d2ab/sage/interfaces/sage0.py There's another expect interface used in the notebook: https://github.com/sagemath/sagenb/blob/master/sagenb/interfaces/expect.py#L204 I'm not sure the exact answer to your original question about disabling readline, but I hope the above helps. Thanks, Jason -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] Re: Turning off readline
On Tuesday, December 11, 2012 9:15:20 AM UTC-5, Jason Grout wrote: Sage has an expect interface for Sage: http://hg.sagemath.org/sage-main/file/33242a07d2ab/sage/interfaces/sage0.py Thanks, Jason. I did not know that. I'll have a look. (As you know, I'm trying to pick up the sage: prompt, the ... sub prompts, etc., that a student would see if they typed it in letter for letter.) Regards, Jim -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] Re: Turning off readline
On 2012-12-11, Jim Hefferon jim.heffe...@gmail.com wrote: --=_Part_251_9537975.1355234826734 Content-Type: text/plain; charset=ISO-8859-1 On Tuesday, December 11, 2012 7:45:10 AM UTC-5, Dima Pasechnik wrote: is pyreadline really used by Sage? It seems to be only needed on Windows, where Sage does not run. Thanks for your comment. Probably I have it wrong. I based my opinion on this from the Sage FAQ: http://wiki.sagemath.org/faq#Why_is_Sage.27s_command_history_different_than_Magma.27s buttressed by the fact that if you type garbage into the repl then Sage gives an error message that refers to the ipython console. But evidence that I am wrong is that I also see readline-6.2.p3.spkg in my /usr/local/sage/spkg/standard directory, so I could be convinced either way. if you look at sage/misc/readline_extra_commands.pyx you'll see that it is basically an interface to GNU readline. Looking into it, one gathers that changing the line readline 1 to readline 0 in the file $HOME/.sage/ipython/ipythonrc (a.k.a. $DOTSAGE/ipython/ipythonrc) disables readline. I tried this for me, it worked. YMMV. HTH, Dmitrii Assuming that Sage uses GNU readline, I spelunked the readline manual looking for a way to disable either dynamically or at startup and did not see anything. I also have spent some time trying to influence the behavior of readline via INPUTRC, as here bash$ INPUTRC=./inputrc sage but I observed no effect (in ./inputrc I tried setting horizontal-scroll-mode=off). Could easily be my cluelessness that caused it to not work, though. Obviously I'm thrashing here, so I'm glad for any insight. -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] RuntimeError when computing Heilbronn Matries
The following error comes out when I try to compute Heilbronn-Merel matries with n=5 in sage: - sage: H=HeilbronnMerel(5) - RuntimeError Traceback (most recent call last) /home/guests/sage-5.4.1/ipython console in module() /home/guests/sage-5.4.1/local/lib/python2.7/site-packages/sage/modular/modsym/heilbronn.so in sage.modular.modsym.heilbronn.HeilbronnMerel.__init__ (sage/modular/modsym/heilbronn.c:5185)() /home/guests/sage-5.4.1/local/lib/python2.7/site-packages/sage/modular/modsym/heilbronn.so in sage.modular.modsym.heilbronn.HeilbronnMerel._initialize_list (sage/modular/modsym/heilbronn.c:5343)() RuntimeError: Floating point exception -- I have no idea why this happens or how to fix it. Is it possible to solve this problem in sage? -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] Re: Simplifying expression, 'x' vs. 'y'
On Tuesday, 11 December 2012 13:15:09 UTC, kcrisman wrote: I wouldn't worry about it, since in general there is no way to define simpler expression that is fully useful at all times, and for more complicated expressions more detail work would be needed anyway. Pedantic Note. Jacques Carette's paper: Understanding Expression Simplification. Proc. ISSAC 2004 (ed. J. Gutierrez), ACM Press, New York, 2004, pp. 72-79. http://www.cas.mcmaster.ca/~carette/publications/simplification.pdf. defines it in a useful way, just not in a computable way (that I can see in practice). -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
[sage-support] Re: Simplifying expression, 'x' vs. 'y'
On Tuesday, December 11, 2012 6:52:53 PM UTC-5, JamesHDavenport wrote: On Tuesday, 11 December 2012 13:15:09 UTC, kcrisman wrote: I wouldn't worry about it, since in general there is no way to define simpler expression that is fully useful at all times, and for more complicated expressions more detail work would be needed anyway. Pedantic Note. Jacques Carette's paper: Understanding Expression Simplification. Proc. ISSAC 2004 (ed. J. Gutierrez), ACM Press, New York, 2004, pp. 72-79. http://www.cas.mcmaster.ca/~carette/publications/simplification.pdf. defines it in a useful way, just not in a computable way (that I can see in practice). Very interesting paper. I guess I was referring to the sense that (1+x)(1-x) and 1-x^2 might each be considered simpler depending on the context, which is the way a lot of people who don't know about decidability would perceive this question (or so my experience has been interacting with a lot of people who ask about why Sage doesn't simplify this or that). I suppose the answer to my example would depend on what you pick for your axiomoids? RJF always seems to have a useful comment about these things as well. -- You received this message because you are subscribed to the Google Groups sage-support group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
