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1 ## Copyright (C) 2003 John W. Eaton |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify |
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6 ## it under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} logm (@var{a}) |
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22 ## Compute the matrix logarithm of the square matrix @var{a}. Note that |
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23 ## this is currently implemented in terms of an eigenvalue expansion and |
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24 ## needs to be improved to be more robust. |
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25 ## @end deftypefn |
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26 |
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27 function B = logm (A) |
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28 |
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29 if (nargin != 1) |
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30 usage ("B = logm (A)"); |
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31 endif |
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32 |
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33 [V, D] = eig (A); |
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34 B = V * diag (log (diag (D))) * inv (V); |
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35 |
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36 endfunction |
