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2021-02-08 15:05:08 +0200 | commented answer | vector_field.apply_map before and after vector.display (weird behaviour) Your explanation makes sense, though I thought when the vector_field is called, as in the question, the corresponding representation of the field in spherical chart is updated. |
2021-02-08 14:54:22 +0200 | commented answer | Divergence of inverse square It would have been great, if it had given the dirac solution. |
2021-02-07 04:27:55 +0200 | asked a question | vector_field.apply_map before and after vector.display (weird behaviour) Hello, Recently, I have come a cross a very weird behaviour with vector_field.apply_map function. Here is the case: Consider the following code: Now, if I create a vector field, substitute ph with ph_1 and th with th_1, and then display the resultant vector as I get 0 printed However, If I do the same, but this time if I add show(v.display()) before calling apply_map function as I get printed (as expected). Why does the display function affect the substitution? |
2021-02-07 00:15:43 +0200 | asked a question | Divergence of inverse square Hello, I tried to calculate the divergence of 1/r^2e_r, but I got zero, where it should have been 4pidirac_delta(re_r) Results is Can this be considered as a bug? |
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2021-02-01 12:30:45 +0200 | commented answer | subs in vector field I had the same confusion. There is the subs function, but doesn't do the job. Don't you guys think that this is a bug? |
2021-02-01 04:11:15 +0200 | asked a question | subs in vector field Hello, gives back the vector field without substituting the value of a How does the funciton subs work with vector fields? Thanks alot for your help. |
2021-01-30 23:43:42 +0200 | commented answer | 2 sets of coordinates in EuclideanSpace? Thank you so much! this is really awesome. I love the way sagemath handle these things. |
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2021-01-29 21:28:08 +0200 | asked a question | 2 sets of coordinates in EuclideanSpace? Hello, I would like to work with 2 vectors in EuclideanSpace each having x1,y1,z1 and x2,y2,z2 coordinates. I will be needing to switch back and forth between cartesian and spherical coordinates as well. As an example, say, (r1,0,0) -> (x1,y1,z1) while (r2,0,0)->(x2,y2,z2) in the same EuclideanSpace. How would one work with multiple vectors (with independent coordinates) in EuclideanSpace? Should one define 2 chart for spherical coordinates and 2 for cartesian coordinates? Or should one create 2 different EuclideanSpace and combine them (if possible)? |
2021-01-29 14:26:30 +0200 | commented answer | Matrix multiplication with a vector in EuclideanSpace Thank you very much. This really helped and saved me from a lot of trouble. |
2021-01-29 01:25:10 +0200 | asked a question | Matrix multiplication with a vector in EuclideanSpace Hello Oversimplified version of my question is "How can I multiply a vector with a matrix?" The only work around I could think of is or directly on the vector field With this approach I have to put the transformed components back in the vector field defined within EuclideanSpace. I would like to use EuclideanSpace to work with vectors. Is there an easy way to handle this? Basically I am looking for an easy way to transform a vector field defined in EuclideanSpace? Thanks in advance for your help. |
2020-07-06 20:18:16 +0200 | commented answer | plot_vector_field3d in spherical coordinates Is there a way to increase density of the vectors? It is also very slow. Is there a way to speed it up? |
2020-07-05 23:00:12 +0200 | answered a question | How do I solve cos(2*t)==sin(t) You could try which gives Z's are integers. |
2020-07-05 22:47:56 +0200 | asked a question | Metric of EuclideanSpace(3) in spherical frame I may have some conceptual misunderstandings, but here is the code I was expecting the diagonal elements of the metric to be What I am doing wrong? |
2020-07-05 22:29:52 +0200 | commented answer | plot_vector_field3d in spherical coordinates Thank you so much. Yep, I made typos. Sorry for that. The code was on another computer, I was typing it it. |
2020-07-04 19:02:31 +0200 | answered a question | How to find all maximum length lists with a nested and display? As the other contributors have said, you can simply use python. Just another version: |
2020-07-04 12:48:23 +0200 | asked a question | plot_vector_field3d in spherical coordinates Hello, How can I draw a vector field in spherical coordinates? For example This beutifully gives me a vector field as Now, I would like to plot this field in spherical coordinates I also tried out the |
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2020-06-22 23:19:56 +0200 | commented answer | assume gives false for a<oo Thanks for the clarification. I think it is an important point of view. |
2020-06-22 18:52:47 +0200 | marked best answer | solve: Possible bug? Hello, This question is relevant to Question #2 in the topic "desolve: wrong solution?!". If desolve is using solve internally when initial conditions are invoked to find the constants after obtaining the general solution, perhaps this is where the problem lies. Consider the following expression sol is [a == (-5/8)] Now, if we plug that back in f, this gives 1.00000000000000 - 1.73205080756888*I, where it ought to give -2 (if there is a solution) And I tried this with Mathematica also It returns an empty list {} for this, indicating that there is no solution. What is wrong with Sage's solve function here? Update: I tried solve with "sympy" agorithm. It agreed with Mathematica. It looks like there is a problem with Maxima |
2020-06-21 18:42:01 +0200 | asked a question | assume gives false for a<oo Hello Why does this code print |
2020-06-21 03:57:16 +0200 | commented question | Another: dirac_delta integration: possible bug? I looked at the code and tried to fix it to accomodate this problem but I wasn't very successful (though I learned a lot!)
I tried the following with your version, but I am getting am I using it wrong? (especially the assumptions?) |
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2020-06-20 15:21:20 +0200 | marked best answer | Integration of dirac_delta Hello, When I tried to integrate the following I get But when I integrate I get If I try the same with Mathematica, I get I get What is the reason of this behaviour of Sage? |