org.netlib.lapack
Class Dgelss

java.lang.Object
  org.netlib.lapack.Dgelss

public class Dgelss
extends java.lang.Object

Following is the description from the original
Fortran source.  For each array argument, the Java
version will include an integer offset parameter, so
the arguments may not match the description exactly.
Contact seymour@cs.utk.edu with any questions.


 *     ..
 *
 *  Purpose
 *  =======
 *
 *  DGELSS computes the minimum norm solution to a real linear least
 *  squares problem:
 *
 *  Minimize 2-norm(| b - A*x |).
 *
 *  using the singular value decomposition (SVD) of A. A is an M-by-N
 *  matrix which may be rank-deficient.
 *
 *  Several right hand side vectors b and solution vectors x can be
 *  handled in a single call; they are stored as the columns of the
 *  M-by-NRHS right hand side matrix B and the N-by-NRHS solution matrix

 *  X.
 *
 *  The effective rank of A is determined by treating as zero those
 *  singular values which are less than RCOND times the largest singular

 *  value.
 *
 *  Arguments
 *  =========
 *
 *  M       (input) INTEGER
 *          The number of rows of the matrix A. M >= 0.
 *
 *  N       (input) INTEGER
 *          The number of columns of the matrix A. N >= 0.
 *
 *  NRHS    (input) INTEGER
 *          The number of right hand sides, i.e., the number of columns
 *          of the matrices B and X. NRHS >= 0.
 *
 *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 *          On entry, the M-by-N matrix A.
 *          On exit, the first min(m,n) rows of A are overwritten with
 *          its right singular vectors, stored rowwise.
 *
 *  LDA     (input) INTEGER
 *          The leading dimension of the array A.  LDA >= max(1,M).
 *
 *  B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
 *          On entry, the M-by-NRHS right hand side matrix B.
 *          On exit, B is overwritten by the N-by-NRHS solution
 *          matrix X.  If m >= n and RANK = n, the residual
 *          sum-of-squares for the solution in the i-th column is given
 *          by the sum of squares of elements n+1:m in that column.
 *
 *  LDB     (input) INTEGER
 *          The leading dimension of the array B. LDB >= max(1,max(M,N)).
 *
 *  S       (output) DOUBLE PRECISION array, dimension (min(M,N))
 *          The singular values of A in decreasing order.
 *          The condition number of A in the 2-norm = S(1)/S(min(m,n)).
 *
 *  RCOND   (input) DOUBLE PRECISION
 *          RCOND is used to determine the effective rank of A.
 *          Singular values S(i) <= RCOND*S(1) are treated as zero.
 *          If RCOND < 0, machine precision is used instead.
 *
 *  RANK    (output) INTEGER
 *          The effective rank of A, i.e., the number of singular values

 *          which are greater than RCOND*S(1).
 *
 *  WORK    (workspace/output) DOUBLE PRECISION array, dimension (LWORK)

 *          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
 *
 *  LWORK   (input) INTEGER
 *          The dimension of the array WORK. LWORK >= 1, and also:
 *          LWORK >= 3*min(M,N) + max( 2*min(M,N), max(M,N), NRHS )
 *          For good performance, LWORK should generally be larger.
 *
 *          If LWORK = -1, then a workspace query is assumed; the routine
 *          only calculates the optimal size of the WORK array, returns
 *          this value as the first entry of the WORK array, and no error
 *          message related to LWORK is issued by XERBLA.
 *
 *  INFO    (output) INTEGER
 *          = 0:  successful exit
 *          < 0:  if INFO = -i, the i-th argument had an illegal value.
 *          > 0:  the algorithm for computing the SVD failed to converge;
 *                if INFO = i, i off-diagonal elements of an intermediate
 *                bidiagonal form did not converge to zero.
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

Dgelss()

Method Summary

static void

dgelss(int m, int n, int nrhs, double[] a, int _a_offset, int lda, double[] b, int _b_offset, int ldb, double[] s, int _s_offset, double rcond, intW rank, double[] work, int _work_offset, int lwork, intW info)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Dgelss

public Dgelss()

Method Detail

dgelss

public static void dgelss(int m,
                          int n,
                          int nrhs,
                          double[] a,
                          int _a_offset,
                          int lda,
                          double[] b,
                          int _b_offset,
                          int ldb,
                          double[] s,
                          int _s_offset,
                          double rcond,
                          intW rank,
                          double[] work,
                          int _work_offset,
                          int lwork,
                          intW info)