In linear algebra, a matrix is in echelon form if it has the shape resulting of a Gaussian elimination. Row echelon form means that Gaussian elimination has operated on the rows and column echelon form means that Gaussian elimination has operated on the columns. In other words, a matrix is in column echelon form if its transpose is in row echelon form. Therefore only row echelon forms are considered in the remainder of this article. The similar properties of column echelon form are easily deduced by transposing all the matrices.

http://en.wikipedia.org/wiki/Row_echelon_form

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Note added at 31 minutos (2012-11-29 18:03:56 GMT)
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http://es.wikipedia.org/wiki/Matriz_escalonada