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20140629 03:15:29 +0200  marked best answer  Mystery white border around Graphics object If you try to show() a sage.plot.graphics.Graphics object, you will find something extremely bizarre: there is a white border around the .png image which is 30 pixels wide (on some sides, 31 pixels wide). There is no documentation of this and it seems to be impossible to remove with any documented options to show() or to the settings of a Graphics object. Does anyone know how to get rid of this bug? The best thing I came up with was to do This only reduced the number of pixels but didn't remove the border entirely. Example: yields: 
20140629 03:15:29 +0200  marked best answer  speed and order of operations with CDF Why is the absolute value of the exponential of z: about twice as fast as the exponential of the real part of z: Should I ignore this kind of thing in sage, or is there a good reason in this particular case? Data: 625 loops, best of 3: 2.94 µs per loop 625 loops, best of 3: 5.87 µs per loop Nonfast_callable times, in case you are interested: 625 loops, best of 3: 1.02 ms per loop 625 loops, best of 3: 988 µs per loop 
20140629 03:14:36 +0200  marked best answer  "Abstract" linear algebra This is more of a general question about whether we can do with Sage what we normally do as mathematicians on paper and in our minds. For example, if I do V = VectorSpace(QQ,4) W = VectorSpace(QQ,4) V==W I get: True. This is quite disturbing  while V and W are isomorphic they should not be identical. As I understand it, a vectorspace over QQ for Sage is just QQ^4, that's it. In other words, the Linear algebra package, while excellent, is not really about vector spaces but rather about arrays of numbers. Any thoughts on this desire of mine to have a genuine "coordinatefree" approach? 
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20130513 18:55:20 +0200  marked best answer  multivariate power series computation with recognition First, a personal comment: For technical implementation of power series, there is a difference between "lazy" power series and "truncated" power series. It sounds like you're interested in the former, but Sage implements the latter. There are different tradeoffs for the two approaches; please don't suggest that one is "improper" unless you're prepared to make a very thorough case that it is uniformly inferior. To have real weight, such a case would probably need to be accompanied by an actual implementation of the other approach. Now on to your specific question: I think the calculations you're interested in can be done just fine with truncated power series. The essential paradigm change is that you need to decide at the outset how many coefficients you're interested in actually computing. This will be the "precision" of the power series that you work with. For multivariable power series, the precision limits the total degree of terms. So in a power series with precision 5, terms like Every power series ring (in Sage) has a default precision  the precision that it assigns by default to elements that don't already have one. This is only important in your case because Here is some code that would carry out your calculation through total degree 4: If you really only need 
20130502 02:25:32 +0200  asked a question  multivariate power series computation with recognition I would like to do a computation in Sage involving formal power series but I believe some (all?) steps may be impossible:
Which of these steps do you believe is possible in Sage? I could write my own software to deal with formal power series properly, but then I would not be able to recognize or simplify the resulting coefficients. As an example:

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20121129 01:03:49 +0200  marked best answer  how to tell if a function is admissible as a 'symbolic' function Actually, this is somewhat misleading, since under the hood, but I hope you get the point. See also Trac 12455 for this very issue  maybe you can help? 
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20121128 11:12:31 +0200  commented answer  how to tell if a function is admissible as a 'symbolic' function This helps but actually gives an even better example of my problem: sage: type(airy_ai); type(gamma) type 'function' type 'function' sage: taylor(gamma(x),x,1) (x  1)*euler_gamma + 1 sage: taylor(airy_ai(x),x,2) TypeError: Cannot evaluate symbolic expression to a numeric value. 
20121128 00:34:06 +0200  asked a question  how to tell if a function is admissible as a 'symbolic' function Sorry for the wording of the question. Functions in sage.functions.special, such as airy_ai, seem not to be true functions, e.g. you can't apply taylor() to them. On the other hand, maxima.airy_ai seems to be OK. How can I tell what "status" a function has, or whether I can pass it to operations such as taylor()? 1/363^(2/3)x^4/gamma(1/3) + 1/183^(1/3)x^3/gamma(2/3)  1/33^(2/3)x/gamma(1/3) + 1/3*3^(1/3)/gamma(2/3) Traceback (click to the left of this block for traceback) ... TypeError: Cannot evaluate symbolic expression to a numeric value. 
20121128 00:20:38 +0200  commented answer  Keeping sage worksheets in sync across computers thanks, that makes it even easier. 
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20121124 12:33:34 +0200  answered a question  Keeping sage worksheets in sync across computers One thing that seems to work is to start the sage notebook from the terminal session with to create a notebook in the specified directory and then use the same command for any other linked computer. I've tried this out and it seems to work perfectly using Dropbox. 
20121124 11:55:18 +0200  commented answer  Mystery white border around Graphics object I think the plot must contain the information of its dimensions, so perhaps we can programmatically do this 
20121124 01:18:02 +0200  asked a question  Keeping sage worksheets in sync across computers I have been using Sage through the notebook interface. I usually keep my other working documents in sync using Dropbox. What do you think is an efficient way of working on notebooks from different computers? Currently I export and import .sws files. I thought of perhaps changing the DATA path to a folder on Dropbox, but I don't know enough about the internals of Sage to see if this would be a horrible idea. 
20121123 02:19:42 +0200  marked best answer  Mystery white border around Graphics object This seems to be a feature from matplotlib. You can try your best, turning off everything in matplotlib like this: The outcome of the plot will be the same as the following code in Sage: So there is not much that can be done on Sage side. Eventually, the generation of the figure and the saving is handled by matplotlib. Update: There is a way to do it in matplotlib. 
20121122 18:01:16 +0200  marked best answer  "Abstract" linear algebra I like coordinatefree linear algebra, but your issue here may simply be that sage: 3 == Mod(3,7) True sage: 3 == Mod(3,5) True sage: Mod(3,5) == Mod(3,7) False sage: Q = PolynomialRing(QQ,'t') sage: 3 == Q(3) True sage: 3 in Q True sage: R = PolynomialRing(RR,'w,v') sage: 3 == R(3) True sage: Q(3) == R(3) False Given this behavior, I don't find it particularly surprising that Of course,
So it seems it's not even _possible_ to make two separate copies of a free module with a given rank. That seems a little limiting, which is your original point, I guess :) Maybe it's more accurate to think of 