On Jul 18, 3:48 pm, Johhannes <dajo.m...@web.de> wrote: > thnx. > > I see that the problem can be also formulated as marix problem. but > the way i did it is in this case the more natural one for me. > is there any reason why it only works this way and solve does not lead > to any result?
For me it looks like: In solve, when writting a == b you assume that a and b are expressions involving several variables. If a and b are expressions, then a == b is also an expression. However, p and x*p1+y*p2 are NOT expressions, but vectors. And equality of vectors is not the same as equality of expressions sage: x == y x == y sage: type(_) <type 'sage.symbolic.expression.Expression'> sage: vector([x]) == vector([y]) False sage: type(_) <type 'bool'> So, in fact, you are passing the following command: sage: [x * p1 + y * p2 == p] [False] sage: solve([False],x,y) Which has no solution. It is subtle, but I would not consider it a bug. If you really want to use solve, you may try the following: sage: solve(x * p1 + y * p2 - p,x,y) [[x == (1/4), y == (3/4)]] In this case, the input is a vector, that is an iterable, so solve extracts its components and equals them to zero. Being said that, I recommend you to use the linear algebra interpretation that I suggested, since it will probably be much more efficient. -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
