2020-02-27 20:59:46 -0600 received badge ● Famous Question (source) 2020-02-27 20:59:46 -0600 received badge ● Notable Question (source) 2019-03-03 15:42:38 -0600 received badge ● Notable Question (source) 2018-07-18 05:49:42 -0600 received badge ● Notable Question (source) 2018-03-24 03:43:14 -0600 received badge ● Popular Question (source) 2017-11-28 00:08:25 -0600 received badge ● Popular Question (source) 2017-08-01 08:25:34 -0600 received badge ● Student (source) 2017-01-23 11:00:06 -0600 received badge ● Popular Question (source) 2017-01-15 07:49:34 -0600 received badge ● Famous Question (source) 2016-09-19 02:37:46 -0600 received badge ● Popular Question (source) 2016-09-18 15:51:22 -0600 received badge ● Notable Question (source) 2016-08-01 19:45:40 -0600 received badge ● Popular Question (source) 2016-02-25 04:45:54 -0600 received badge ● Famous Question (source) 2015-11-19 04:02:26 -0600 received badge ● Notable Question (source) 2015-11-19 04:02:26 -0600 received badge ● Popular Question (source) 2015-10-20 14:32:38 -0600 received badge ● Notable Question (source) 2015-10-20 14:32:38 -0600 received badge ● Popular Question (source) 2015-03-26 22:10:10 -0600 marked best answer Solving linear matrix equations Hi everybody, I'm new to Sage and I'm pretty confused with the solving of matrix equations, I didn't fully understand the guide. I've got these vectors: V_fa = vector([V_f*cos(phi), V_f*sin(phi), 0]) V_ra = vector([V, 0, 0]) omega = vector([0, 0, L*psi_d]) P = vector([0, L*psi_d, 0])  And i want to implement the equation: V_fa=V_ra+omega.cross_product(P)  to isolate and obtain the value of psi_d. How can I do that? Thank you very much 2015-01-14 03:41:20 -0600 commented answer Transpose of a column vector Thank you for your reply. May I ask you what is the difference between a list and a vector? 2015-01-12 16:17:55 -0600 received badge ● Commentator 2015-01-12 16:17:55 -0600 commented answer Transpose of a column vector I need to transpose the vector because when i use it in a sum it says unsupported operand parent(s) for '+': 'Full MatrixSpace of 3 by 1 dense matrices over Symbolic Ring' and 'Vector space of dimension 3 over Symbolic Ring' , so i thought maybe it was because it had to be a row vector. Why if i do v.row() it still says row() takes at least 1 positional argument (0 given) ? 2015-01-12 12:04:10 -0600 asked a question Transpose of a column vector Hi, I've got a column vector and I need to transpose it. But when i do: v=v.column() it says column() takes at least 1 positional argument (0 given) I've also tried doing v=Matrix([[1, 0, 0],[0, 1, 0], [0, 0, 1],])*v.column() which worked before but still doesn't work. What is the problem here? Thank you 2015-01-12 06:57:17 -0600 commented answer Derivative of a function Thank you so much!! 2015-01-12 05:52:24 -0600 asked a question Derivative of a function Hi, I've got this two functions: psi=function('psi',t) psi_d=function('psi_d',t) psi=(sin(delta(t))*v(t))/(l*cos(delta(t))) psi_d=diff(psi)  but it says No differentiation variable specified how can I derivate psi? Please someone help me it's driving me crazy since yesterday! Thank you very much 2015-01-11 15:34:34 -0600 commented answer Equations solving Now the problem is that when i do solve(eqq1,diff(psi(t))) he doesn't solve it (it gives me [ ]), and if i do solve(eqq1,diff(psi)) is says No differentiation variable specified. What's wrong? 2015-01-11 15:29:02 -0600 commented answer Equations solving Ok i got it, i just had to writeeqq1=eqq1.subs(V_f==V_ff) 2015-01-11 15:25:55 -0600 commented answer Equations solving I redefined eqq1, but doing like this it ignores the left part of the equation, so eqq1 becomes just sin(delta(t))*v/cos(delta(t)) 2015-01-11 14:27:36 -0600 commented answer Equations solving It works! Grazie mille! ;) Now i substituted that value in the second equation doing eqq1.left().subs(V_f==V_ff) but when i do solve(eqq1,diff(psi)) it gives me diff(psi(t))=V_f*sin(delta(t))/l like i never did that substitution before. What can i do to have diff(psi(t))=[v(t)*tan(delta(t))]/l as a solution? 2015-01-11 13:16:36 -0600 asked a question Equations solving Hi everybody, i've got this two equations: eqq0: V_f*cos(delta(t))=v(t) eqq1: V_f*sin(delta(t))=l*diff(psi(t))  I need to isolate V_f from the first equation, obtaining V_f=v(t)/cos(delta(t)) and substitute it in the second equation. Then i have to isolate diff(psi(t))=[v(t)*tan(delta(t))]/l. I did : a=solve (eqq0,V_f) V_ff=a.right()  but it says "AttributeError: 'Sequence_generic' object has no attribute 'right'" How can i solve this two equations? Thank you. 2014-12-23 03:49:24 -0600 edited question Sum of two vectors Hi everybody, i've got this functions and variables: v = function('v',t) a_V_ra = function('a_V_ra',t) a_a_ra=function('a_a_ra',t) g = var('g') r_V_ra = vector([v,0,0]) a_V_ra = R_ra*r_V_ra.column()  where R is a matrix and a_V_ra is the vector [cos(psi(t))v(t), sin(psi(t))v(t),0]. But when i do this: a_a_ra = diff(a_V_ra)+vector([0,0,-g])  it says: TypeError: unsupported operand parent(s) for '+': 'Full MatrixSpace of 3 by 1 dense matrices over Symbolic Ring' and 'Vector space of dimension 3 over Symbolic Ring' I guess it's saying that i'm summing a matrix and a vector, but they're both vectors! What can I do to make it work? Thank you. 2014-12-23 03:49:24 -0600 received badge ● Editor (source)