Re: Marking pivot elements in a matrix?

*To*: mathgroup at smc.vnet.net*Subject*: [mg74939] Re: Marking pivot elements in a matrix?*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Thu, 12 Apr 2007 04:48:20 -0400 (EDT)*Organization*: Uni Leipzig*References*: <evhuev$34o$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, and somthing like: ShowPivotmark[matrix_?MatrixQ, index_] := (RowBox[{"(", GridBox[matrix /. m_?MatrixQ :> ReplacePart[m, StyleBox[ Part[matrix, Sequence @@ index], FontColor -> Red, FontWeight -> "Bold"], index], RowLines -> Table[If[j == First[ index], True, False], {j, Last[Dimensions[m]]}], ColumnLines -> Table[If[i == Last[index], True, False], {i, First[Dimensions[ m]]}]], ")"}] // DisplayForm) with m = Table[Random[Integer, {-2, 2}], {4}, {4}] ShowPivotmark[m, {3, 2}] does not help ?? Regards Jens jackgold at umich.edu wrote: > Hi folks, > > I am writing notes for a class in which matrix manipulations > is a necessary and frequent task. At present, when I wish to pick an > entry of the matrix as a "pivot" I simply write "pivot > on {2, 3}". It would be nice to enclose the {2, 3} entry in a square or > circle to indicate it is the pivot entry. I am unable to do this. In > this same vein, I often have need to put a single vertical (horizontal) > line through the matrix. > Mathematica provides the means for putting vertical (horizontal) > lines in a matrix but it allows only the option of putting lines at > every column (row). I want to be more selective, say one line > just before the last column. (This is the standard way of indicating > that the last column is an augmentation to the original coefficient > matrix). > > Is there any reasonably simple way to do this? >