Man Scilab

ereduc Scilab Function

ereduc - computes matrix column echelon form by qz transformations

Calling Sequence

[E,Q,Z [,stair [,rk]]]=ereduc(X,tol)

Parameters

X : m x n matrix with real entries.
tol : real positive scalar.
E : column echelon form matrix
Q : m x m unitary matrix
Z : n x n unitary matrix
stair : vector of indexes,
- * ISTAIR(i) = + j if the boundary element E(i,j) is a corner point.
- * ISTAIR(i) = - j if the boundary element E(i,j) is not a corner point.
(i=1,...,M)
rk : integer, estimated rank of the matrix

Description

Given an m x n matrix X (not necessarily regular) the function ereduc computes a unitary transformed matrix E=Q*X*Z which is in column echelon form (trapezoidal form). Furthermore the rank of matrix X is determined.

Examples


X=[1 2 3;4 5 6]
[E,Q,Z ,stair ,rk]=ereduc(X,1.d-15)

Author

Th.G.J. Beelen (Philips Glass Eindhoven). SLICOT