Bug in RowReduce of a matrix with symbolic entries

*To*: mathgroup at smc.vnet.net*Subject*: [mg70772] Bug in RowReduce of a matrix with symbolic entries*From*: "Ruben" <r.tiger74 at gmail.com>*Date*: Fri, 27 Oct 2006 00:28:08 -0400 (EDT)

Hi all, the Mathematica help browser claims that one can apply RowReduce to a matrix with numbers and letters, however that's not true, try to row-reduce the following augmented matrix: Clear[x, y, z, s, t]; RowReduce[{{ 1, 1, 1, x}, {-2, -1, -1, y}, {-3, -3, -2, z}, {0, 2, 2, s}, {-2, -4, -5, t}}] // MatrixForm the output does not contain any expression involving the letters! Am I doing something wrong? For the sake of completeness, one can obtain the right answer (the homogeneous system that makes the above augmented matrix consistent) by typing: Clear[a, v, x, y, z, s, t]; a = {{1, 1, 1}, {-2, -1, -1}, {-3, -3, -2}, {0, 2, 2}, {-2, -4, -5}}; answer = NullSpace[Transpose[a]]; v = {x, y, z, s, t}; Thread[answer.v == 0] (I found this method in this google group). Thanks for any suggestion you may provide. Ruben.