SparseM (version 0.74)

lsq: Least Squares Problems in Surveying

Description

One of the four matrices from the least-squares solution of problems in surveying that were used by Michael Saunders and Chris Paige in the testing of LSQR

Usage

data(lsq)

format

A list of class matrix.csc.hb or matrix.ssc.hb depending on how the coefficient matrix is stored with the following components:

• ra

{ra component of the csc or ssc format of the coefficient matrix, X. } ja{ja component of the csc or ssc format of the coefficient matrix, X. } ia{ia component of the csc or ssc format of the coefficient matrix, X. } rhs.ra{ra component of the right-hand-side, y, if stored in csc or ssc format; right-hand-side stored in dense vector or matrix otherwise.} rhs.ja{ja component of the right-hand-side, y, if stored in csc or ssc format; a null vector otherwise.} rhs.ia{ia component of the right-hand-side, y, if stored in csc or ssc format; a null vector otherwise.} xexact{vector of the exact solutions, b, if they exist; a null vector o therwise.} guess{vector of the initial guess of the solutions if they exist; a null vector otherwise.} dim{dimenson of the coefficient matrix, X.} rhs.dim{dimenson of the right-hand-side, y.} rhs.mode{storage mode of the right-hand-side; can be full storage or same format as the coefficient matrix.}

References

Koenker, R and Ng, P. (2002). SparseM: A Sparse Matrix Package for R, http://www.econ.uiuc.edu/~roger/research

Matrix Market, http://math.nist.gov/MatrixMarket/data/Harwell-Boeing/lsq/lsq.html

See Also

read.matrix.hb

Examples

data(lsq)
class(lsq) # -> [1] "matrix.csc.hb"
model.matrix(lsq)->X
class(X) # -> "matrix.csr"
dim(X) # -> [1] 1850  712
y <- model.response(lsq) # extract the rhs
length(y) # [1] 1850