# [?] Reduced Row Echelon form

Posted 5 months ago
907 Views
|
3 Replies
|
2 Total Likes
|
 Hi,Mathematica 12 produces: m = {{1 , 3, 4, b1}, {-4, 2, -6, b2}, {-3, -2, -7, b3}} RowReduce[m] {{1, 0, 13/7, 0}, {0, 1, 5/7, 0}, {0, 0, 0, 1}} Wolfram Alpha produces the expected result with the variables b1,b2 and b3 in the result How should I interprete the result from Mathematica, why 2 different results?Kind regards, Bert Answer
3 Replies
Sort By:
Posted 5 months ago
 RowReduce in the Wolfram Language gives generic results. W|A makes more of an effort at what might, only partly facetiously, be termed "mind reading". One can achieve a similar effect using Reduce. mat = {{1, 3, 4, b1}, {-4, 2, -6, b2}, {-3, -2, -7, b3}}; vars = Array[x, 3]; lhs = mat[[All, 1 ;; -2]] rhs = Map[Last, mat] (* Out= {{1, 3, 4}, {-4, 2, -6}, {-3, -2, -7}} Out= {b1, b2, b3} *) Reduce[lhs.vars == rhs, vars] (* Out= b1 == b2/2 - b3 && x == (7 b2)/26 - (3 b3)/13 + (5 x)/13 && x == -(b2/13) - b3/13 - (7 x)/13 *) Answer
Posted 5 months ago
 Thank you for this answer Daniel. But what is a generic result? Answer
Posted 5 months ago
 A generic result is one that holds for almost all values of the parameters (in the measure theory sense of the term). Answer