Program name:       LLSQ

Authors names:      Charles L. Lawson and Richard J. Hanson    

Address:            Not given

Telephone Number:   Not given

Suggested Donation: None

Program Description: 

LLSQ is a package of fourteen basic, high-quality mathematical FORTRAN 
subprograms which can be utilized for your applications programming.  These 
first appeared in the "IMSL Numerical Computations News letter", "User 
News", and/or "Directions", and are reprinted here with only editorial 
changes.

The following lists the subprogram names and provides a brief statement of 
the usage of each module.


Subroutine                       Purpose

 - NNLS        Solve a constrained least squares problem Ax ~ b, subject
               to all solution components being non-negative.  Using LDP,
               one of the other codes, a least squares solution of systems
               Ax ~ b, subject to general inequality constraints Gx >= h
               can be found.

 - SVA and     Solve a least squares problem Ax ~ b using the singular
   SVDRS       value decomposition of the matrix A.

 - HFTI        Solve a least squares problem Ax ~ b using the Golub-
               Businger algorithm for least squares problems.

 - BNDACC and  Solve a least squares problem Ax ~ b using Householder
   BNDSOL      transformations.  This subprogram works with a banded
               matrix that arises in curve or surface fitting of discrete
               data by B-splines, for example.
 
The user must generally provide input and output of data to all the 
routines.  With the exception of routine SVA, the subprograms in the package 
do not do any significant reading or writing of data.
 
These routines are exceptionally well documented in the Prentice-Hall book, 
"Solving Least Squares Problems", by Charles L. Lawson and Richard J. 
Hanson.  This book is, in fact, almost a prerequisite to properly use these 
routines.   
 
The sources on this disk were provided on tape by IMSL.  Thanks to 
Exploration Systems, Inc., for the use of their PRIME computer used to 
convert the source from tape to disk.
 
For additional information, or a little help, write to me, Jeff Fried, c/o 
PC-SIG TECHNICAL DEPARTMENT.

System requirements aren't listed.  If you have a FORTRAN compiler on your 
system, you should be able to use these modules.