Language Reference |

**provides updating and downdating for rank deficient linear
least squares solutions, complete orthogonal factorization,
and Moore-Penrose inverses**

**CALL LUPDT(***lup, bup, sup, , , , , ssq>***);**

The LUPDT subroutine returns the following values:

*lup*- is an lower triangular matrix that
is updated or downdated by using the rows in .
*bup*- is an matrix of right-hand sides that
is updated or downdated by using the rows in .
If is not specified,
*bup*is not accessible. *sup*- is a vector of square roots of residual sum of squares
that is updated or downdated by using the rows in .
If
*ssq*is not specified,*sup*is not accessible.

The inputs to the LUPDT subroutine are as follows:

- specifies an lower triangular matrix
to be updated or downdated by row vectors
stored in the matrix .
Only the lower triangle of is used; the
upper triangle can contain any information.
- is a matrix used rowwise
to update or downdate the matrix .
- specifies an optional matrix
of right-hand sides that have to be
updated or downdated simultaneously with .
If is specified, the argument must be specified.
- specifies an optional matrix used rowwise
to update or downdate the right-hand-side matrix .
*ssq*- specifies an optional vector that, if is specified, specifies the square root of the error sum of squares that should be updated or downdated simultaneously with and .

The relevant formula for the LUPDT call is . See the example in the documentation for the RZLIND call.

Copyright © 2009 by SAS Institute Inc., Cary, NC, USA. All rights reserved.