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20140628 20:14:49 0500  marked best answer  ValueError: free variable x > x when plotting the function x Hi all. I got the following problem: this raises If I replace How can I do ? My rationale behind my question is that I have a class which takes a function as argument and can perform many thinks on it, among other the plot. I made the following : My point in doing so is that I have to accept, as input My questions :

20140628 20:14:47 0500  marked best answer  get_minmax_data on implicit_plot This is a sequel of my question about plotting level set. In the following, G is a circle : The "correct" get_minmax_data sould be As far as I understood the code (and the thread "Retrieving xy data from implicit plots" on Sagesupport), the following is the relevant part : in ../plot/contour_plot.py My questions are :

20140628 20:14:47 0500  marked best answer  Plot the level sets of a function I'm trying to draw level set of a function f:R^2>R, that is the set of solutions of f(x,y)=h for a given h. For that purpose I wrote the following This works, but I'm not satisfied principally because I got the level sets under the form of a list of functions. Moreover it will not work if the level set is vertical. Thus I would prefer to get the solution under the form of a parametric curve. Does Sage provides something for that ? 
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20131219 22:43:02 0500  commented answer  Solve equation 1/3*x + sin(2*x)==1 Thanks for your answer, tmonteil. That solves the equation with enough accuracy for my purpose but it does not solves my full problem because I have a system. Ultimately I would like to know the intersection points of two curves. In my example the second curve was too easy : y1=0. Since many painting softwares are able to fill the region between two curves (e.g. pstricks), I guess this is possible ... 
20131214 20:26:48 0500  asked a question  Solve equation 1/3*x + sin(2*x)==1 Hi all. I have the equations and I want solutions. I know by the intermediate value theorem that there are two solutions : about x=0.5 and x=1.25. I'd like Sage to give me these solutions. I already tried to_poly_solve=True and/or explicit_solutions=True. As an example of failure : What can I do ? Thanks Laurent Claessens 
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20120929 04:09:05 0500  asked a question  PolynomialRing and from __future__ import unicode_literals Hello TypeError Traceback (most recent call last) /home/moky/script/<ipython console=""> in <module>() /home/moky/Sage/local/lib/python2.7/sitepackages/sage/rings/polynomial/polynomial_ring_constructor.pyc in PolynomialRing(base_ring, arg1, arg2, sparse, order, names, name, implementation) 425 if R is None: 426 raise TypeError("invalid input (%s, %s, %s) to PolynomialRing function; please see the docstring for that function"%( > 427 base_ring, arg1, arg2)) 428 429 return R TypeError: invalid input (Rational Field, x, None) to PolynomialRing function; please see the docstring for that function I guess this is the same kind of problem that the one in this question By the way, this is "fixed" by using 
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20120520 02:55:23 0500  answered a question  convert expression to function Does it answer the question ? 
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20120408 05:20:14 0500  commented question  get_minmax_data too generosous ? By the way, what is the correct way to know the global xmin,xmax,ymin and ymax of a function ? A 3digit approximation is enough. Up to now I'm using get_minmax_data, but is it the correct way ? 
20120408 04:32:35 0500  asked a question  get_minmax_data too generosous ? Hello I'd like to understand the rationale behind the I would have expected ymin to be 0. Is is a bug or is it something I don't understand ? 
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20120321 21:53:15 0500  commented answer  min(x,y)=x ... and then plot3d f(x,y)=min(x,y) Yes, `min_symbolic` is the answer. Thanks :) 
20120321 21:52:24 0500  marked best answer  min(x,y)=x ... and then plot3d f(x,y)=min(x,y) I can't find this, but I'm pretty sure there is another question with this on ask.sagemath.org. I think if you use the latter, all should be well. I hope? Don't have time to try now. Good luck! 
20120321 10:05:43 0500  asked a question  min(x,y)=x ... and then plot3d f(x,y)=min(x,y) Hi all I can understand the following somewhat surprising result : A friend of mine wants to plot3d the function that a human should write f(x,y)=min(x,y) what she does is of course, it does not produce the expected result because of what I said in introduction about min(x,y). By the way : So ... well ... what do I have to say to her ? What is the best way to plot a function (in the math sense of the term) when it cannot be managed by a function (in the Sage sense of the term). The following works : I guess that will also work. So my questions are :
Thanks for any help have a good night Laurent Claessens (on the night timezone :) ) 
20120302 22:00:28 0500  answered a question  Type error in recursion Your error is not due to recursion. The following example (slightly simplified with respect to yours) produces the same error : The error is at x*f(3). f(3) is a function, not a number. I don't really understand what you are trying to do. Some kind of factorial ? The following code does not produce the error : Note : f(n1)(3) Hope it helps Laurent 
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20120202 00:58:11 0500  asked a question  Sage for (very) undergrad students Hi all Today I had hard time with Sage because This is not the primitive my students are expecting : they expect 1x on the denominator. In particular they are not expecting : I had other some small problems like that with Sage like the difference between +Inf,Inf and Inf when computing a limit (in the latter case my students are expecting "does not exist"). So my question is : is there a way to ask Sage to behave like a very undergrad student is expected to behave ? (ex : ln(1) does not exist) Is there a way to say «I'm an undergrad student and I want Sage to solve my homework of basics calculus» ? Do you have experience/habits to prevent Sage to mislead students by its unexpected answers (however mathematically correct) ? 
20120126 18:25:54 0500  answered a question  solve and calculate A variation on the Shashank'answer : Here you consider the function "solution of the equation as function of z", and you do whatever with it. 