20190721 06:05:17 0500  answered a question  Is there a way to temporarily turn off sage's type checking? Personally I would try to find a way to avoid the symbolic ring (with If you want to use the symbolic ring, then you have to do the conversion to a Assuming this setup: You can do it e.g. like this: and use it as follows: You can convert constraints too: for example: It is reasonable that there is no coercion from the Symbolic Ring to Linear functions over RDF, because it would not be welldefined with respect to the ordering of variables: e.g. coercion of two functions of different variables would depend on the order in which you do it. The function above "suffers" from the same (but probably you don't care). 
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20190716 14:13:00 0500  answered a question  Plotting derivative of bump function This is definitely a bug; I reported it as trac ticket #28207. As a workaround, you can plot the derivative manually: For linear combinations, you can use linearity of the derivative (as a workaround). 
20190716 13:29:49 0500  answered a question  How to define polynomial p(x_i, x_j) while x_i, x_j runs over available variables? I suppose our multivariate polynomial ring Now it depends a little bit on how your bivariate polynomial is defined. Is it a Python function? A Sage callable symbolic expression? An element of a polynomial ring? An element of the symbolic ring? If it is a Python function: If it is a Sage callable expression: If it is an element of the symbolic ring: If it is a polynomial in a polynomial ring: All give the same result, a list of elements of You can add other conditions in the list comprehension using Also you can use And you don't have to use indices if your condition doesn't depend on it: 
20190716 12:39:58 0500  answered a question  Create Matrix in RREF with indeterminates Here's a way. First we define our variables: Then we introduce the following function: The For example: We can test all the combinations: Output: 
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20190711 04:16:33 0500  answered a question  How to generate a nonsquare Vandermonde matrix? Enter The relative inefficiency here (taking powers instead of repeatedly multiplying) is copied from the original. Then you can do for instance: 
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20190710 13:00:34 0500  commented answer  Defining manifolds in a systematic way. That should work (and it does for me). What version of SageMath are you running? 
20190710 11:51:26 0500  answered a question  Defining manifolds in a systematic way. See the documentation on charts, particularly the arguments For example, you can do the following: 
20190709 15:26:03 0500  answered a question  Does the set_embedding command have a bug? Setting the combinatorial embedding does not immediately affect how the graph is plotted. However, you can call one of the layout algorithms that use this combinatorial embedding, such as Indeed we get clockwise 1, 2, 3, 4, 5. Edit: Obviously not clockwise but counterclockwise. I opened trac ticket #28152 for this issue. 
20190709 14:51:50 0500  commented question  Does the set_embedding command have a bug? Please include a full code sample, since 
20190709 06:35:31 0500  commented question  Does the set_embedding command have a bug? Please edit your question: paste the relevant code, select it and press the 
20190708 13:41:08 0500  answered a question  How to turn the function into expression? Suppose we have an ordinary function or (which is the same, but shorter) Evaluating the function at arguments of the desired type, we can work with the result, e.g. symbolically: or with polynomials: However, the latter variant does not work when because it will always output a symbolic expression. So in order to work with polynomials, you have to do: instead (or better: define an ordinary function, as above). In my opinion, this is one of the reasons why having this notation for callable symbolic expressions is bad. Side note: in SageMath it is often very reasonable to use expressions instead of functions. Many facilities are designed around this, accepting an expression and a list of variables, so the expression will be interpreted as a function of the specified variables. For example, to take a derivative with 
20190625 14:44:03 0500  answered a question  (Update) How to change/set variables? Here's how you can do substitution into the coefficients of a differential form, in a simple example: 
20190625 14:29:44 0500  commented question  (Update) How to change/set variables? Also note the variables 
20190625 14:06:04 0500  commented question  (Update) How to change/set variables? Updating the original forms is pointless. What you want to do is a substitution in the components of 
20190616 04:16:32 0500  answered a question  solve equation with two variables over RR This is a bug; I reported it as trac ticket #27998. 
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20190609 01:23:05 0500  answered a question  roots of polynomial It is the multiplicity of the respective root. Try factoring the polynomial with 
20190609 01:15:13 0500  answered a question  roots of polynomial It is the multiplicity of the respective root. Try factoring the polynomial with 
20190607 03:24:14 0500  answered a question  Problems and errors in solve an equation This is a quartic polynomial in Take plusminus the square roots of these solutions to get the solutions for 
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20190604 14:13:51 0500  answered a question  Adding elements to a set The documentation on sets explains it well:
So If you want a mutable set, just use Python's 
20190601 06:13:32 0500  answered a question  How to handle elements of two different Galois fields simultaneously? The modulus should be a polynomial over the prime field. To get the generator of, say, 
20190530 10:19:34 0500  commented question  Sagemath not evaluating complicated expression I reported this (sub)issue as trac ticket #27897. 
20190530 09:56:08 0500  commented question  Sagemath not evaluating complicated expression There seems to be some weird "holding" going on, e.g. 
20190529 15:56:10 0500  commented question  How to perform modulus in polynomial rings..

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20190522 17:05:02 0500  commented answer  Formal determinant of symbolic matrix Easier would be to implement the determinant separately, for matrices with ordinary entries, but as a formal sum. 
20190522 15:58:31 0500  answered a question  Formal determinant of symbolic matrix You can implement your own "ring" as described in How to implement new algebraic structures in Sage. Here's a start: Now you can do: Note that this is a hack because the thing is not actually a ring, e.g. 
20190522 03:09:40 0500  commented question  What does cohomology_generators actually do? I said "suggest" because the code obviously doesn't work, as you demonstrated. 
20190521 12:46:39 0500  commented question  What does cohomology_generators actually do? Strictly speaking the documentation does not claim that the list is anyhow minimal. However the stated algorithm does suggest that this is attempted. Do you see anything wrong with the algorithm or its implementation (approx. 40 lines of code)? 
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20190520 06:29:43 0500  commented question  Maximum algebraic connectivity from a given collection of graphs 
20190520 04:44:52 0500  commented answer  Maximum algebraic connectivity from a given collection of graphs It's more efficient to let nauty restrict the number of edges: 
20190517 05:33:29 0500  commented question  Is there any way to plot3d latex package on sagemath? Please add the code you have so far to your question. 
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