Issue 1168: Matrix([[x+y, -x, 0], [-x-y, x, 1], [0,1,0]]).inf() gives wrong result http://code.google.com/p/sympy/issues/detail?id=1168
New issue report by ondrej.certik: In [1]: A = Matrix([[x+y, -x, 0], [-x-y, x, 1], [0,1,0]]) In [2]: Ainv = A.inv("ADJ") In [3]: Ainv Out[3]: ⎡ -1 -x ⎤ ⎢────── 0 ──────⎥ ⎢-x - y -x - y⎥ ⎢ ⎥ ⎢ 0 0 1 ⎥ ⎢ ⎥ ⎣ 1 1 0 ⎦ In [4]: Ainv*A Out[4]: ⎡ x y ⎤ ⎢- ────── - ────── 0 0⎥ ⎢ -x - y -x - y ⎥ ⎢ ⎥ ⎢ 0 1 0⎥ ⎢ ⎥ ⎣ 0 0 1⎦ In [6]: (Ainv*A).applyfunc(simplify) Out[6]: ⎡1 0 0⎤ ⎢ ⎥ ⎢0 1 0⎥ ⎢ ⎥ ⎣0 0 1⎦ This is a-ok. But this is wrong: In [1]: A = Matrix([[x+y, -x, 0], [-x-y, x, 1], [0,1,0]]) In [2]: Ainv = A.inv() In [3]: Ainv = Ainv.applyfunc(simplify) In [4]: Ainv Out[4]: ⎡0 0 0⎤ ⎢ ⎥ ⎢0 0 1⎥ ⎢ ⎥ ⎣0 1 0⎦ In [5]: Ainv * A Out[5]: ⎡ 0 0 0⎤ ⎢ ⎥ ⎢ 0 1 0⎥ ⎢ ⎥ ⎣-x - y x 1⎦ It needs to be investigated if the error is in simplify() or in the inversion algorithm. See also this thread: http://groups.google.com/group/sympy/browse_thread/thread/313238d56bbaea21 Issue attributes: Status: Accepted Owner: ---- Labels: Type-Defect Priority-High WrongResult -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy-issues" group. To post to this group, send email to sympy-issues@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sympy-issues?hl=en -~----------~----~----~----~------~----~------~--~---