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 Matrix Operator Method Gottfried Ultimate Fellow Posts: 766 Threads: 119 Joined: Aug 2007 08/27/2007, 03:09 PM (This post was last modified: 08/27/2007, 03:12 PM by Gottfried.) bo198214 Wrote:Hm, then I somewhere must have an error in my computation. I wanted to compute the Matrix logarithm via the formula $\log(A)=\sum_{n=1}^\infty \frac{(-1)^{n+1}}{n} (A-I)^n$. For A being the power derivation matrix of $e^x$ at 0, i.e. truncated to 6x6Hmm, I can crosscheck such a computation in the evening. But for a quick reply: did you observe the partial sums for the entries for increasing n by s_n_(i,j) = sum (k=1..n) entry_(i,j)? If their sign oscillate we have a candidate for the Euler-summation (for each entry separately!). Another try may be to use the alternate series for logarithm let f=(a-1)*(a+1) ^-1 log(a) = f/1 + f^3/3 + f^5/5 ... (don't have it at hand, whether this series actually has alternating signs, but I think, it's correct). The same formula can be used for matrices A, where (A+I) is invertible and *all* the eigenvalues of (A+I) are in the admissible range for this series. Anyway, it is worth to look at the partial sums; Euler-summation of the low order 2 can sum for instance 1-2+4-8+16-...+... which is even more divergent than many of our sums, requiring only few terms for a good approximation of the final result. For a more detailed discussion I can do better in the evening. Gottfried Gottfried Helms, Kassel « Next Oldest | Next Newest »

 Messages In This Thread Matrix Operator Method - by Gottfried - 08/12/2007, 08:08 PM RE: Matrix Operator Method - by bo198214 - 08/13/2007, 04:15 AM RE: Matrix Operator Method - by jaydfox - 08/13/2007, 05:40 AM RE: Matrix Operator Method - by Gottfried - 08/13/2007, 09:22 AM RE: Matrix Operator Method - by bo198214 - 08/14/2007, 03:43 PM RE: Matrix Operator Method - by Gottfried - 08/14/2007, 04:15 PM RE: Matrix Operator Method - by bo198214 - 08/26/2007, 12:18 AM RE: Matrix Operator Method - by Gottfried - 08/26/2007, 11:24 AM RE: Matrix Operator Method - by bo198214 - 08/26/2007, 11:39 AM RE: Matrix Operator Method - by Gottfried - 08/26/2007, 04:22 PM RE: Matrix Operator Method - by Gottfried - 08/26/2007, 10:54 PM RE: Matrix Operator Method - by bo198214 - 08/27/2007, 08:29 AM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 11:04 AM RE: Matrix Operator Method - by bo198214 - 08/27/2007, 11:35 AM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 11:58 AM RE: Matrix Operator Method - by bo198214 - 08/27/2007, 12:13 PM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 01:19 PM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 02:29 PM RE: Matrix Operator Method - by bo198214 - 08/27/2007, 02:36 PM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 03:09 PM RE: Matrix Operator Method - by bo198214 - 08/27/2007, 07:15 PM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 08:15 PM RE: Matrix Operator Method - by bo198214 - 08/29/2007, 05:28 PM RE: Matrix Operator Method - by Gottfried - 08/27/2007, 12:43 PM RE: Matrix Operator Method - by Gottfried - 10/08/2007, 12:11 PM RE: Matrix Operator Method - by Gottfried - 10/14/2007, 09:32 PM RE: Matrix Operator Method - by Gottfried - 04/04/2008, 09:41 AM RE: Matrix Operator Method - by Gottfried - 04/17/2008, 09:21 PM RE: Matrix Operator Method - by bo198214 - 04/25/2008, 03:39 PM RE: Matrix Operator Method - by Gottfried - 04/26/2008, 06:09 PM RE: Matrix Operator Method - by bo198214 - 04/26/2008, 06:47 PM RE: Matrix Operator Method - by Gottfried - 04/18/2008, 01:55 PM RE: Matrix Operator Method - by Gottfried - 07/08/2008, 06:46 AM Diagonalization for dxp/basic facts/Pari-routine - by Gottfried - 08/08/2008, 01:12 PM Exact entries for T-tetration Bell-matrix - by Gottfried - 09/24/2008, 08:22 PM RE: Exact entries for T-tetration Bell-matrix - by bo198214 - 09/26/2008, 07:30 AM RE: Exact entries for T-tetration Bell-matrix - by Gottfried - 09/26/2008, 09:56 AM

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