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1 ## Copyright (C) 2014 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 it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## @deftypefn {Built-in Function} {[@var{L}, @var{U}, @var{P}, @var{Q}] =} luinc (@var{A}, '0') |
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20 ## @deftypefnx {Built-in Function} {[@var{L}, @var{U}, @var{P}, @var{Q}] =} luinc (@var{A}, @var{droptol}) |
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21 ## @deftypefnx {Built-in Function} {[@var{L}, @var{U}, @var{P}, @var{Q}] =} luinc (@var{A}, @var{opts}) |
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22 ## |
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23 ## @code{luinc} is deprecated and will be removed in Octave version 4.6. |
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24 ## Please use @code{ilu} or @code{ichol} in all new code. |
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25 ## |
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26 ## Produce the incomplete LU@tie{}factorization of the sparse matrix @var{A}. |
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27 ## Two types of incomplete factorization are possible, and the type |
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28 ## is determined by the second argument to @code{luinc}. |
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29 ## |
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30 ## Called with a second argument of @qcode{'0'}, the zero-level incomplete |
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31 ## LU@tie{}factorization is produced. This creates a factorization of @var{A} |
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32 ## where the position of the nonzero arguments correspond to the same |
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33 ## positions as in the matrix @var{A}. |
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34 ## |
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35 ## Alternatively, the fill-in of the incomplete LU@tie{}factorization can |
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36 ## be controlled through the variable @var{droptol} or the structure |
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37 ## @var{opts}. The @sc{umfpack} multifrontal factorization code by Tim A. |
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38 ## Davis is used for the incomplete LU@tie{}factorization, (availability |
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39 ## @url{http://www.cise.ufl.edu/research/sparse/umfpack/}) |
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40 ## |
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41 ## @var{droptol} determines the values below which the values in the |
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42 ## LU@tie{} factorization are dropped and replaced by zero. It must be a |
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43 ## positive scalar, and any values in the factorization whose absolute value |
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44 ## are less than this value are dropped, expect if leaving them increase the |
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45 ## sparsity of the matrix. Setting @var{droptol} to zero results in a complete |
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46 ## LU@tie{}factorization which is the default. |
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47 ## |
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48 ## @var{opts} is a structure containing one or more of the fields |
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49 ## |
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50 ## @table @code |
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51 ## @item droptol |
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52 ## The drop tolerance as above. If @var{opts} only contains @code{droptol} |
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53 ## then this is equivalent to using the variable @var{droptol}. |
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54 ## |
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55 ## @item milu |
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56 ## A logical variable flagging whether to use the modified incomplete |
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57 ## LU@tie{} factorization. In the case that @code{milu} is true, the dropped |
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58 ## values are subtracted from the diagonal of the matrix @var{U} of the |
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59 ## factorization. The default is @code{false}. |
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60 ## |
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61 ## @item udiag |
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62 ## A logical variable that flags whether zero elements on the diagonal of |
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63 ## @var{U} should be replaced with @var{droptol} to attempt to avoid singular |
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64 ## factors. The default is @code{false}. |
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65 ## |
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66 ## @item thresh |
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67 ## Defines the pivot threshold in the interval [0,1]. Values outside that |
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68 ## range are ignored. |
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69 ## @end table |
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70 ## |
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71 ## All other fields in @var{opts} are ignored. The outputs from @code{luinc} |
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72 ## are the same as for @code{lu}. |
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73 ## |
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74 ## Given the string argument @qcode{\"vector\"}, @code{luinc} returns the |
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75 ## values of @var{p} @var{q} as vector values. |
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76 ## @seealso{ilu, ichol, lu, sparse} |
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77 ## @end deftypefn |
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78 |
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79 ## Deprecated in version 4.2 |
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80 |
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81 function retval = usage (varargin) |
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82 |
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83 persistent warned = false; |
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84 if (! warned) |
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85 warned = true; |
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86 warning ("Octave:deprecated-function", |
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87 "luinc is obsolete and will be removed from a future version of Octave, please use ilu or ichol instead"); |
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88 endif |
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89 |
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90 retval = __luinc__ (varargin{:}); |
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91 |
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92 endfunction |
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93 |
