There are two separate things going on here. I think this is a bug:
sage: vector(range(3)) TypeError: unable to find a common ring for all elements since this does work: sage: vector(srange(3)) (0, 1, 2) The difference is that the elements of range(3) are python ints while the elements of srange(3) are Sage Integers. It also works if you specify the coordinate ring: sage: vector(RR,range(3)) (0.000000000000000, 1.00000000000000, 2.00000000000000) sage: vector(ZZ,range(3)) (0, 1, 2) The problem lies in the function prepare() in sage/modules/free_module_element.pyx, since Sequence(range(3)) has universe <type 'int'> and is_Ring() fails on that. The fix would therefore appear to be to test for the case where the universe is <type 'int'> and change it to ZZ. The second issue is just that after w=range(3), w is a python list, and for lists, multiplying by 2 just repeats the list. Similarly sage: range(3) + range(3) [0, 1, 2, 0, 1, 2] If you want to do mathematical operations such as scalar multiplcation, convert to a vector. (You could also do [2*i for i in range(3)], but I don't think you like that construction.) I have CC's this to sage-devel so that the bug will be fixed (if people agree with me that i is a bug). John Cremona 2008/8/28 Stan Schymanski <[EMAIL PROTECTED]>: > Dear all, > > I use pylab for plotting, which requires creating lists of x and y > values. Now, in order to manipulate the lists, I would like to perform > simple operations on them, like for example multiply by 2. However, > lists seem to behave very differently to vectors when performing > mathematical operations on them (see below). Is there an easy way of > converting between lists and vectors to use them in mathematical > computations without having to loop through all elements? Intuitively, > I thought that vector(list) would work to convert a list to a vector, > but it does not (see below). > > Thanks already for your help, and I'm sorry if I missed this issue in > the documentation. > > Stan > > ---------------------------------------------------------------------- > | SAGE Version 3.1.1, Release Date: 2008-08-17 | > | Type notebook() for the GUI, and license() for information. | > ---------------------------------------------------------------------- > > sage: v = vector([1,2,3]); v > (1, 2, 3) > sage: 2*v > (2, 4, 6) > sage: w=range(1,4); w > [1, 2, 3] > sage: 2*w > [1, 2, 3, 1, 2, 3] > sage: w1=vector(w) > --------------------------------------------------------------------------- > TypeError Traceback (most recent call > last) > > /Users/sschym/modelling/VegPat/<ipython console> in <module>() > > /Users/sschym/modelling/VegPat/free_module_element.pyx in > sage.modules.free_module_element.vector (sage/modules/ > free_module_element.c:2376)() > > /Users/sschym/modelling/VegPat/free_module_element.pyx in > sage.modules.free_module_element.prepare (sage/modules/ > free_module_element.c:2622)() > > TypeError: unable to find a common ring for all elements > > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
