[sage-support] shortest paths in graphs
This works:
graphs.CubeGraph(4).shortest_paths('')
but this don't:
graphs.CubeGraph(4).shortest_path_all_pairs()
Maybe the shortest_path_all_pairs function needs a
by_weight=False parameter too (like the other shortest paths
functions).
I also would like to have a function all_shortest_paths(u,v), which
returns all shortest paths from u to v.
I know i could use all_paths and then pick the shortest, but that's
really inefficient.
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[sage-support] Re: noncommutative algebras
Dear William, On Feb 22, 1:58 am, William Stein [EMAIL PROTECTED] wrote: If I rename it to tensor.sage (not sure if this is a good idea), Yes, that's a VERY GOOD idea. It's really crazy to use a compiled spyx for the purposes of interfacing with the Singular interpreter via pexpect. Sorry, using a compiled spyx was just, well, let's call it my personal tradition. Am i right that the loop must be re-written if it is .sage rather than .spyx? I think for i from 1=i=len(L[2]): is only possible in .spyx, while in .sage it should be for i in range(1,len(L[2])+1) @John, this would explain the new error message after renaming the file. However, i don't know why attaching the .spyx didn't work. Yours Simon --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Errno 13 on worksheet cells after uploading
Hello, After uploading a worksheet from my PC to the sagenb.org server, I can't edit or evaluate cells within it. I'm receiving the error message Traceback (most recent call last): File stdin, line 1, in module IOError: [Errno 13] Permission denied: '/home/server2/sage_notebook/ worksheets/aprestech/4/code/3.py' Did I do something wrong, or is this a bug? Thanks, Andy --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Trying to graph cubic function f(x)=x^(1/3)
I am interested in the use of Sage as a teaching tool at all grade levels. At the moment, I'm trying to weave Sage into an introductory algebra curriculum. I can graph all the basic functions with plot(x), replacing x with x^2, x^3, 1/x, etc. The one I can't get to work is x^(1/3). I've tried to express the cube root function several different ways. The expression I'm using now is: sage: show(plot(x^(1/3),-10,10),figsize=[5,5],xmin=-10,xmax=10,ymin=-10,ymax=10) I receive the error message TypeError: 'float' object is unsubscriptable Also, is the expression above the most succinct way to generate a graph with this kind of view, x and y ranging -10 to 10? Thanks for any advice. Andy --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Trying to graph cubic function f(x)=x^(1/3)
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi Andy, I had the exact same question a few days ago. There are many issues involved here, but the short answer to your question (provided by Carl Witty) is: you can plot x^(1/3) with show(plot(lambda x : RR(x).nth_root(3), -10, 10), figsize=[5,5], ymin=-10, ymax=10) You don't need to specify xmin and xmax in show since they're given in the plot command. Best, Alex Andy wrote: | I am interested in the use of Sage as a teaching tool at all grade | levels. At the moment, I'm trying to weave Sage into an introductory | algebra curriculum. | | I can graph all the basic functions with plot(x), replacing x with | x^2, x^3, 1/x, etc. The one I can't get to work is x^(1/3). I've | tried to express the cube root function several different ways. The | expression I'm using now is: | | sage: | show(plot(x^(1/3),-10,10),figsize=[5,5],xmin=-10,xmax=10,ymin=-10,ymax=10) | | I receive the error message TypeError: 'float' object is | unsubscriptable | | Also, is the expression above the most succinct way to generate a | graph with this kind of view, x and y ranging -10 to 10? | | Thanks for any advice. | | Andy | | | - -- Alexandru Ghitza Assistant Professor Department of Mathematics Colby College Waterville, ME 04901 http://bayes.colby.edu/~ghitza/ -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHvtngdZTaNFFPILgRAvbjAJ9qlM5R2UnmCHwOMV2HOlhg+LcwZACcC21K Mrx/wRMSjGXeYz2KpkXN0Xo= =O3v+ -END PGP SIGNATURE- --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Trying to graph cubic function f(x)=x^(1/3)
On Fri, Feb 22, 2008 at 6:19 AM, Alex Ghitza [EMAIL PROTECTED] wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi Andy, I had the exact same question a few days ago. There are many issues involved here, but the short answer to your question (provided by Carl Witty) is: you can plot x^(1/3) with show(plot(lambda x : RR(x).nth_root(3), -10, 10), figsize=[5,5], ymin=-10, ymax=10) You don't need to specify xmin and xmax in show since they're given in the plot command. Hi, What would people think of improving the _error_ message to plot so that it prints some additional helpful information for certain strikingly common situations? +1 ? -1? -- William Andy wrote: | I am interested in the use of Sage as a teaching tool at all grade | levels. At the moment, I'm trying to weave Sage into an introductory | algebra curriculum. | | I can graph all the basic functions with plot(x), replacing x with | x^2, x^3, 1/x, etc. The one I can't get to work is x^(1/3). I've | tried to express the cube root function several different ways. The | expression I'm using now is: | | sage: | show(plot(x^(1/3),-10,10),figsize=[5,5],xmin=-10,xmax=10,ymin=-10,ymax=10) | | I receive the error message TypeError: 'float' object is | unsubscriptable | | Also, is the expression above the most succinct way to generate a | graph with this kind of view, x and y ranging -10 to 10? | | Thanks for any advice. | | Andy | | | - -- Alexandru Ghitza Assistant Professor Department of Mathematics Colby College Waterville, ME 04901 http://bayes.colby.edu/~ghitza/ -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHvtngdZTaNFFPILgRAvbjAJ9qlM5R2UnmCHwOMV2HOlhg+LcwZACcC21K Mrx/wRMSjGXeYz2KpkXN0Xo= =O3v+ -END PGP SIGNATURE- -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Errno 13 on worksheet cells after uploading
On Thu, Feb 21, 2008 at 9:09 PM, AprèsTech [EMAIL PROTECTED] wrote: Hello, After uploading a worksheet from my PC to the sagenb.org server, I can't edit or evaluate cells within it. I'm receiving the error message Traceback (most recent call last): File stdin, line 1, in module IOError: [Errno 13] Permission denied: '/home/server2/sage_notebook/ worksheets/aprestech/4/code/3.py' Did I do something wrong, or is this a bug? This is *definitely* a bug on my part. I'll look into it immediately. If you still have this problem after you get this email, please respond and let me know. Also, can you get the bug to occur again by uploading another worksheet? This problem is caused by the too-strict in this case security model. It can be fixed once for all if it is easily repeatable. William --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: noncommutative algebras
On Fri, Feb 22, 2008 at 12:50 AM, Simon King [EMAIL PROTECTED] wrote: Dear William, On Feb 22, 1:58 am, William Stein [EMAIL PROTECTED] wrote: If I rename it to tensor.sage (not sure if this is a good idea), Yes, that's a VERY GOOD idea. It's really crazy to use a compiled spyx for the purposes of interfacing with the Singular interpreter via pexpect. Sorry, using a compiled spyx was just, well, let's call it my personal tradition. Am i right that the loop must be re-written if it is .sage rather than .spyx? I think for i from 1=i=len(L[2]): is only possible in .spyx, while in .sage it should be for i in range(1,len(L[2])+1) Yes, that is correct. But when you're not working with pure C data structures you're going to get no speed improvements by using for i from 1=i=len(L[2]): instead of for i in range(1,len(L[2])+1) You're just making things a little more difficult. @John, this would explain the new error message after renaming the file. Yes, that would. However, i don't know why attaching the .spyx didn't work. That's very suspicious: sage: attach tensorpower.spyx Loading of file /Users/palmieri/.sage/tensorpower.spy has type not implemented. That suggests there is either a very very weird serious bug that got magically fixed or maybe the above log isn't what really happened -- notice that in the error message it says .spy not .spyx. -- William --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: noncommutative algebras
On Fri, Feb 22, 2008 at 10:03 AM, John Palmieri [EMAIL PROTECTED] wrote: On Feb 22, 8:47 am, William Stein [EMAIL PROTECTED] wrote: On Fri, Feb 22, 2008 at 12:50 AM, Simon King [EMAIL PROTECTED] wrote: Dear William, On Feb 22, 1:58 am, William Stein [EMAIL PROTECTED] wrote: If I rename it to tensor.sage (not sure if this is a good idea), Yes, that's a VERY GOOD idea. It's really crazy to use a compiled spyx for the purposes of interfacing with the Singular interpreter via pexpect. Sorry, using a compiled spyx was just, well, let's call it my personal tradition. Am i right that the loop must be re-written if it is .sage rather than .spyx? I think for i from 1=i=len(L[2]): is only possible in .spyx, while in .sage it should be for i in range(1,len(L[2])+1) Yes, that is correct. But when you're not working with pure C data structures you're going to get no speed improvements by using for i from 1=i=len(L[2]): instead of for i in range(1,len(L[2])+1) You're just making things a little more difficult. @John, this would explain the new error message after renaming the file. Yes, that would. However, i don't know why attaching the .spyx didn't work. That's very suspicious: sage: attach tensorpower.spyx Loading of file /Users/palmieri/.sage/tensorpower.spy has type not implemented. That suggests there is either a very very weird serious bug that got magically fixed or maybe the above log isn't what really happened -- notice that in the error message it says .spy not .spyx. Right, I'm confused by that, too, but that's what it says. I just took the new file tensorpower.sage that Simon sent me, copied it to tp.spyx, and did the following (in a new worksheet). sage: attach tp.spyx Loading of file /home/palmieri/.sage/tp.spy has type not implemented. sage: attach tensorpower.sage sage: R=singular.ring(2,'(x1,x12,x2)','dp') sage: D=singular.matrix(3,3,'0,0,-x12, 0,0,0, 0,0,0') sage: S=singular.nc_algebra(1,D) sage: S // characteristic : 2 // number of vars : 3 //block 1 : ordering dp // : namesx1 x12 x2 //block 2 : ordering C // noncommutative relations: ... This is with Sage 2.9.3 on the linux box in my office, and I had a similar problem with Sage 2.10.1 on my mac at home. ... Now, after trying one or two more things, here's more information: if I start sage from a terminal, then type attach tp.spyx, I get an error about not being able to find the file (which makes sense, since I put the file in ~/.sage/, not in my home directory). Then I type notebook(), go to my web browser, and do the stuff I pasted in above. Then I quit that, go back to the terminal, hit ctrl-C twice, and do attach tp.spyx. This time it works: typing notebook() and then quitting it seems to change my default directory from ~/ to ~/.sage/. So, anyway, it seems that I can attach .spyx files from the terminal session, but not from a notebook in a web browser. To attach files in a *local* notebook give the exact path to the file. -- William --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: shortest paths in graphs
Looking at the repository, it seems as if I wrote these functions, but
I don't think that's right. Maybe this was one of the patches I merged
from Jason Grout, while his name wasn't getting on the changesets. I
seem to remember Emily Kirkman working on path functions, also. I'm
not sure what the origin of this code is, but the fact that it doesn't
work has been filed as a trac ticket:
http://trac.sagemath.org/sage_trac/ticket/2265
On Feb 22, 12:20 am, vgermrk [EMAIL PROTECTED] wrote:
This works:
graphs.CubeGraph(4).shortest_paths('')
but this don't:
graphs.CubeGraph(4).shortest_path_all_pairs()
Maybe the shortest_path_all_pairs function needs a
by_weight=False parameter too (like the other shortest paths
functions).
I also would like to have a function all_shortest_paths(u,v), which
returns all shortest paths from u to v.
I know i could use all_paths and then pick the shortest, but that's
really inefficient.
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[sage-support] Re: noncommutative algebras
Dear John,
a brief addendum to a previous post of yours:
On Feb 20, 10:22 pm, John Palmieri [EMAIL PROTECTED] wrote:
By the way, is the following a bug?
sage: singular.LIB('ncall.lib')
sage: R=singular.ring(0,'(x1,x12,x2)','dp')
sage: C=singular.matrix(3,3,'1,-1,-1, -1,1,-1, -1,-1,1')
sage: C
1, -1,-1,
-1,1, -1,
-1,-1,1
sage: R=singular.ring(0,'(x1,x12,x2)','dp')
sage: C
`sage1`
As William pointed out, this is not a bug.
When re-defining R, then i think the matrix C is in fact lost.
However, it may be worth mentioning that after defining the 'same'
ring under a new name, it is easy to produce a copy of C in the new
ring; let R and C be defined as above. Then:
sage: newR=singular.ring(0,'(x1,x12,x2)','dp')
sage: C
`sage1`
sage: newC=R.fetch(C)
sage: newC
1, -1,-1,
-1,1, -1,
-1,-1,1
sage: R.set_ring()
sage: C
1, -1,-1,
-1,1, -1,
-1,-1,1
sage: newC
`sage3`
You see, a matrix (or an ideal) is only accessible if its ring is
active. But as long as the ring is not overwritten, the matrix isn't
lost.
Singular offers two commands to ship data from one ring to another:
fetch and imap. See
http://www.singular.uni-kl.de/Manual/latest/sing_197.htm#SEC237
and
http://www.singular.uni-kl.de/Manual/latest/sing_215.htm#SEC255
Cheers
Simon
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[sage-support] Re: shortest paths in graphs
I also would like to have a function all_shortest_paths(u,v), which returns all shortest paths from u to v. See ticket: http://trac.sagemath.org/sage_trac/ticket/2266 --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Trying to graph cubic function f(x)=x^(1/3)
Alex Thanks for your help. I had searched the group and found the thread about nth roots, but I wasn't putting it together with the plot statement correctly. Thanks also to Jason for publishing an illustration -- good idea. The published worksheets are a great resource for learning Sage and working through the subtleties, one which I'll remember to search for future questions. On Feb 22, 7:19 am, Alex Ghitza [EMAIL PROTECTED] wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi Andy, I had the exact same question a few days ago. There are many issues involved here, but the short answer to your question (provided by Carl Witty) is: you can plot x^(1/3) with show(plot(lambda x : RR(x).nth_root(3), -10, 10), figsize=[5,5], ymin=-10, ymax=10) You don't need to specify xmin and xmax in show since they're given in the plot command. Best, Alex Andy wrote: | I am interested in the use of Sage as a teaching tool at all grade | levels. At the moment, I'm trying to weave Sage into an introductory | algebra curriculum. | | I can graph all the basic functions with plot(x), replacing x with | x^2, x^3, 1/x, etc. The one I can't get to work is x^(1/3). I've | tried to express the cube root function several different ways. The | expression I'm using now is: | | sage: | show(plot(x^(1/3),-10,10),figsize=[5,5],xmin=-10,xmax=10,ymin=-10,ymax=10) | | I receive the error message TypeError: 'float' object is | unsubscriptable | | Also, is the expression above the most succinct way to generate a | graph with this kind of view, x and y ranging -10 to 10? | | Thanks for any advice. | | Andy | | | - -- Alexandru Ghitza Assistant Professor Department of Mathematics Colby College Waterville, ME 04901http://bayes.colby.edu/~ghitza/ -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.7 (GNU/Linux) Comment: Using GnuPG with Mozilla -http://enigmail.mozdev.org iD8DBQFHvtngdZTaNFFPILgRAvbjAJ9qlM5R2UnmCHwOMV2HOlhg+LcwZACcC21K Mrx/wRMSjGXeYz2KpkXN0Xo= =O3v+ -END PGP SIGNATURE- --~--~-~--~~~---~--~~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] sage can't find matlab
Hi there -
I have a local install of Matlab 2007b and a local install of Sage.
When I run a Matlab command from Sage, e.g. the command
matlab.eval('2+2')
I get the error Unable to start matlab because the command 'matlab -
nodisplay' failed. The location of the Matlab executable is included
in my PATH variable, so I'm not sure what the problem is. I've
scoured the various tutorials documentation available, as well as
the Sage wiki, and I couldn't find anyone addressing this issue. Any
suggestions?
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