Re: [sage-support] Re: text3d and latex
Sorry about the confusion, I was just addressing Jason's comment about my work adding coordinate transformations to plot3d. Your example looks cool, Thomas! After #7872 is applied, you'll be able to use spherical_plot3d to make your code more concise :). On Tue, Jan 26, 2010 at 12:53 PM, Thomas Scofield scofi...@calvin.edu wrote: To what does #7872 refer? And is that a reply to O. Lazo, or to my post? On Jan 26, 2010, at 2:56 AM, William Cauchois wrote: Check out #7872, Jason! On Jan 23, 11:59 am, Jason Grout jason-s...@creativetrax.com wrote: Oscar Lazo wrote: On 22 ene, 12:56, Thomas Scofield scofi...@calvin.edu wrote: I have made an interactive notebook for help students understand the meaning of spherical coordinates. It is published at http://www.sagenb.org/home/pub/1400/ You might be interested in the code here: http://www.sagenb.org/home/pub/1319/ Also, Bill Cauchois was working on adding a general coordinate transformation argument to plot3d, based on our discussions about spherical and cylindrical plotting. He worked on this a lot at the Sage Days last week. I'm not sure when he'll submit a patch. I hope he does soon, since I'd really like to use it in my class in February or March! Thanks, Jason -- Jason Grout -- 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org Thomas L. Scofield Associate Professor Department of Mathematics and Statistics Calvin College -- 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org -- 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: text3d and latex
Check out #7872, Jason! On Jan 23, 11:59 am, Jason Grout jason-s...@creativetrax.com wrote: Oscar Lazo wrote: On 22 ene, 12:56, Thomas Scofield scofi...@calvin.edu wrote: I have made an interactive notebook for help students understand the meaning of spherical coordinates. It is published at http://www.sagenb.org/home/pub/1400/ You might be interested in the code here: http://www.sagenb.org/home/pub/1319/ Also, Bill Cauchois was working on adding a general coordinate transformation argument to plot3d, based on our discussions about spherical and cylindrical plotting. He worked on this a lot at the Sage Days last week. I'm not sure when he'll submit a patch. I hope he does soon, since I'd really like to use it in my class in February or March! Thanks, Jason -- Jason Grout -- 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: Problems with 3d plotting
I'm running Ubuntu 9.10. I installed the package sun-java6-plugin and it works for me. On Jan 18, 8:35 am, Jack Fearnley j...@alcor.concordia.ca wrote: I have just compiled sage-4.3 running under ubuntu 9.04 on an IBM pentium machine. The sage directory is in its own partition under /tools. I have no real need for 3d plotting but I was running through the sage tutorial and thought I would check it out. The plot3d command works silently producing no visible output and no error messages. I found that my system lacked java so I downloaded the standard ubuntu version using synaptic. This had no effect on plotting. Any thoughts? Best wishes, Jack Fearnley -- 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
Re: [sage-support] Re: plot3d can't handle log(0)
On Tue, Nov 17, 2009 at 6:08 AM, kcrisman kcris...@gmail.com wrote: Would all these ideas for testing deal with the triangulation issue, Bill? Your original post seems to imply this. - kcrisman I thought that, during triangulation, we could test for NaN values and delete those faces. However, I see now that ParametricSurface.triangulate assumes a regular indexing scheme for the _faces array, so the array must be full. This means that deleting faces must be performed after the mesh has been triangulated, unless we want to change the algorithm significantly. Jason Grout and I actually dealt with these same issues when working on #5514, exclusions for parametric 3D plots, which unfortunately is not entirely finished. Perhaps a better way to get plot3d to handle functions with undefined values would be to finish work on #5514, and then after we encounter undefined values apply a region function (this is the feature that #5514 implements) that serves to exclude those values. I should have recognized this at the beginning! Does that sound like a good course of action? I can definitely revisit #5514. -- 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: plot3d can't handle log(0)
I was looking into this issue this afternoon, and its more complicated
than it might appear at first. Removing a point in a 2D plot is
relatively simple, but when you remove a point in a 3D plot you could
be affecting several faces. There is also the matter that evaluation
is separate from triangulation, so you have to find out how to
communicate the fact that a vertex doesn't exist between the two
stages (since ParametricSurface usually assumes it has a uniform
grid).
If during evaluation you could set the vertex coordinates at a non-
existent point to be some kind of special NaN value, you could omit
that vertex later during triangulation. Does anyone know how you could
get at such a NaN value for Cython doubles?
- Bill
On Nov 10, 12:34 pm, kcrisman kcris...@gmail.com wrote:
In 4.2.1.alpha0:
sage: f(x,y)=ln(x)
sage: P=plot3d(f,(x,0,1),(y,0,1))
sage: P
ERROR: An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line statement', (16,0))
---
ValueError Traceback (most recent call
last)
snip a lot
ValueError: math domain error
Switch to (x,0.1,1), and all is well. I am pretty sure the problem is
that line 404 in plot/plot3d/parametric_surface.pyx doesn't have an
exception handler forlog(0) or other such nan type values:
sage: math.log(0)
snip
ValueError: math domain error
But in the plotting context, it's silly not to just ignore this; we
check for things like this all the time:
sage: plot(log,0,1)
works fine
Unfortunately, I don't know enough about C/Cython to fix this. For
now it would probably be enough to fix it for the z variable. This is
now #7423. Any takers, or hints as to how to fix this? Thanks!
- kcrisman
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[sage-support] Re: z-range issues in implicit_plot3d
Thanks for your work resolving this issue! I will be happy to create a Trac ticket and submit a patch with this change. -- Bill On Nov 8, 7:38 pm, Matt Rissler discn...@gmail.com wrote: Poking through the code I think line 922 in sage/plot/plot3d/implicit_surface.pyx should read: self.zrange= ranges[2][:2] I'd submit the patch myself, but I'd have to create a login and figure out the versioning system. Someday, but not today. Matt On Oct 24, 11:34 pm, Micah micah.ja...@gmail.com wrote: Greetings all, I have been fiddling around withimplicit_plot3dfor most of the day and I have noticed that sometimes, the range of values for z are partially disregarded. sage: implicit_plot3d((x^2)/2+(y^2)/2+(z^2)/2,(x,-5,5),(y,-5,5),(z, 0,5),contour=2) should produce only the northern hemisphere of the sphere of radius sqrt(8) but it produces the entire sphere. Meanwhile sage: implicit_plot3d((x^2)/2+(y^2)/2+(z^2)/2,(x,0,5),(y,0,5), (z,-5,5),contour=2) only produces the portion of the sphere in the first octant, rather than a full quarter of the sphere. Of course, thez-rangeis not always disregarded. sage: implicit_plot3d((x^2)/2+(y^2)/2+(z^2)/2,(x,0,5),(y,-5,5), (z,-5,5),contour=2) produces the expected output. This happens on both 4.1.1 (on sagenb) and 4.1.2 (my installation). For convenience, I've published the sagenb notebook. http://sagenb.org/pub/830/ I have tried tracing through the code, but I was quickly overwhelmed by the task. -Micah --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: plotting and float
By the way, you can make your original example work by using a lambda instead of a symbolic expression: sage: plot3d(lambda x, y: abs(e^(pi*i*x)+e^(pi*i*y)), (0,1), (0,1)) Should work. (Although I'm getting the error plot variables should be distinct, which I think is a bug; workaround is to change one of the lower bounds to 0.1 instead of 0.) --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: plotting and float
It seems to me that the error comes from feeding a function which uses i into fast_float (called by the plotting functions to compile the function to be plotted into an optimized form). I tried a simpler function using i and got the same error: sage: plot3d(x + y + i, (x, 0, 1), (y, 0, 1)) Traceback (click to the left for traceback) ... TypeError: float() argument must be a string or a number sage: from sage.ext.fast_eval import fast_float sage: fast_float(x + i, 'x') Traceback (click to the left for traceback) ... TypeError: float() argument must be a string or a number It would make sense for the low-level representation used by fast_float not to include a concept of imaginary numbers. Have you had success plotting any other functions that use imaginary numbers? There should be a mechanism to fall back to using the unmodified function in the event that fast_float fails to convert the function. --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Null space of a matrix?
Hi, I needed to check the null space of the following matrix: [ -2 7 ] [ 00 ] So I typed: sage: matrix([[-2, 7], [0, 0]]).kernel() And Sage 4.0.rc0 told me that the basis for the resultant vector space was [0, 1]. But this does not seem correct -- [0, 1] does not even satisfy the equation -2x_1 + 7x_2 = 0 that we can read off of the matrix above (if we augment it with [0, 0] in our head). So what's wrong? Is kernel() the right method to use for this? Or did I read the result incorrectly? Or is my reasoning wrong (the possibility that I fear most, since I have a linear algebra final on Monday :D)? --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: Null space of a matrix?
Thanks Jason! I see that right_kernel() also works for this. -- Bill On Sat, Jun 6, 2009 at 5:41 PM, Jason Groutjason-s...@creativetrax.com wrote: William Cauchois wrote: Hi, I needed to check the null space of the following matrix: [ -2 7 ] [ 0 0 ] So I typed: sage: matrix([[-2, 7], [0, 0]]).kernel() And Sage 4.0.rc0 told me that the basis for the resultant vector space was [0, 1]. But this does not seem correct -- [0, 1] does not even satisfy the equation -2x_1 + 7x_2 = 0 that we can read off of the matrix above (if we augment it with [0, 0] in our head). So what's wrong? Is kernel() the right method to use for this? Or did I read the result incorrectly? Or is my reasoning wrong (the possibility that I fear most, since I have a linear algebra final on Monday :D)? Sage returns the *left* nullspace, i.e., the solution to the equation xA=0. You want the right nullspace; so do matrix(...).transpose().kernel(). Jason --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: parametric_plot3d appears to not give the correct axes values, also steals keyboard
I filed a ticket at http://trac.sagemath.org/sage_trac/ticket/6002. -- Bill --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: parametric_plot3d appears to not give the correct axes values, also steals keyboard
On Wed, May 6, 2009 at 12:28 PM, Alden alden.wal...@gmail.com wrote: 0) sagenb.com is awesome, especially since Mathematica 7 takes up 100% of my processor at all times under Ubuntu 9.04. Glad to hear it :). 1) When I run: parametric_plot( (cos(t), sqrt(2)*sin(t)) , (t,0,2*pi)) I get a nice 2d parametric plot, with the top of the ellipse clearly hitting close to 1.5 on the y-axis. When I run: parametric_plot3d( (cos(t), 1 , sqrt(2)*sin(t)), (t,0,2*pi)) The top of the ellipse really looks like it's at z=1, and the whole thing looks a lot like a circle. I realize that this is probably not a problem with sage and rather with whatever is doing the plotting, but I thought I should point it out. I think that this is a bug, but I can't find the source of the error very easily. I will open a Trac ticket to address this issue. Thanks for pointing it out! 2) Also, after clicking and dragging on the 3d plot, I can't type anywhere in firefox (the notebook or the address bar) until I click onto another tab and then back again. This may be a problem with java in my browser not taking the keyboard away from the applet. That's odd. Do you mean to say that even when you try to move focus away from the Java applet using your mouse, input is still captured? I myself use Sage on vanilla Ubuntu 9.0.4 with no difficulties. Maybe the problem is with your Java or web browser configuration. 3-more of a feature request than an error I guess) I have noticed from googling that there has been some discussion about creating a function from R^n to R^m. I am sure there is some good reason why this isn't the case, but I was curious about whether it would be possible to just automatically map everything over tuples of symbolic expressions, or make a tuple of symbolic expressions a symbolic expression itself. For example, why couldn't diff( (t, 2*t), t) (which gives the error that a tuple is not a symbolic expression) notice that the tuple is a tuple of symbolic expressions, and then just map itself over it to get (1,2). Also, then defining f(x,y) = (2*x, 2*y) seems like it would work. Similarly, what if there was a dot product function which just did the obvious thing when it was given two tuples of symbolic expressions? The reason that I am thinking about this is that it would be really awesome if I could tell my vector calculus class to do a line integral by defining what f(c(t)) =fc(t) and c(t) are and then just: integrate( dot( fc(t), diff( c(t), t), t, 0, 2*pi) rather than something like integrate( vector( (t,t^2,t^3) ).dot_product( diff( vector( (t,t,t) ), t ) ), t,0,2*pi) which is a little less intuitive. To address your diff example: it is simple enough in this case to do [diff(f, t) for f in (t, 2*t)]. I don't know what work is being done in Sage to help work with vector-valued functions, but maybe someone more familiar with the symbolic calculus component can chime in. One way to improve your line integral example would be to refactor it into a Python function in terms of f and fc, so that students could simply type: line_integral(f, fc). But since this is a math class, I understand if you do not want to go that in-depth into programming techniques. -- Bill --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
[sage-support] Re: bug in region_plot
I've had to deal with adapt_to_callable a bit, and I too would greatly appreciate an improvement to it. One thing that I think should be handled in adapt_to_callable, or whatever its replacement will be, is plot ranges. Users are usually allowed to explicitly specify variables in plot ranges (this overlaps with adapt_to_callable's variable inference functionality), and I see a lot of duplicated code to extract u_low and u_high from a plot range which may be a 2-tuple or a 3-tuple. In Carl Witty's implicit surface patch (#5249), I wrote a function called extract_vars_ranges_and_adapt which may be worth taking a look at. From the docstring, it makes f into a fast callable function, while inferring its arguments and canonicalizing the provided ranges. This function can be found at line 1193 in http://trac.sagemath.org/sage_trac/attachment/ticket/5249/trac5249.patch Thanks, Bill --~--~-~--~~~---~--~~ 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 For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~--~~~~--~~--~--~---
