All Packages  Class Hierarchy  This Package  Previous  Next  Index

Class org.netlib.lapack.Dgbtrf

java.lang.Object
   |
   +----org.netlib.lapack.Dgbtrf

public class Dgbtrf

extends 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
 *  =======
 *
 *  DGBTRF computes an LU factorization of a real m-by-n band matrix A
 *  using partial pivoting with row interchanges.
 *
 *  This is the blocked version of the algorithm, calling Level 3 BLAS.
 *
 *  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.
 *
 *  KL      (input) INTEGER
 *          The number of subdiagonals within the band of A.  KL >= 0.
 *
 *  KU      (input) INTEGER
 *          The number of superdiagonals within the band of A.  KU >= 0.
 *
 *  AB      (input/output) DOUBLE PRECISION array, dimension (LDAB,N)
 *          On entry, the matrix A in band storage, in rows KL+1 to
 *          2*KL+KU+1; rows 1 to KL of the array need not be set.
 *          The j-th column of A is stored in the j-th column of the
 *          array AB as follows:
 *          AB(kl+ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl)
 *
 *          On exit, details of the factorization: U is stored as an
 *          upper triangular band matrix with KL+KU superdiagonals in
 *          rows 1 to KL+KU+1, and the multipliers used during the
 *          factorization are stored in rows KL+KU+2 to 2*KL+KU+1.
 *          See below for further details.
 *
 *  LDAB    (input) INTEGER
 *          The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
 *
 *  IPIV    (output) INTEGER array, dimension (min(M,N))
 *          The pivot indices; for 1 <= i <= min(M,N), row i of the
 *          matrix was interchanged with row IPIV(i).
 *
 *  INFO    (output) INTEGER
 *          = 0: successful exit
 *          < 0: if INFO = -i, the i-th argument had an illegal value
 *          > 0: if INFO = +i, U(i,i) is exactly zero. The factorization
 *               has been completed, but the factor U is exactly
 *               singular, and division by zero will occur if it is used
 *               to solve a system of equations.
 *
 *  Further Details
 *  ===============
 *
 *  The band storage scheme is illustrated by the following example, when
 *  M = N = 6, KL = 2, KU = 1:
 *
 *  On entry:                       On exit:
 *
 *      *    *    *    +    +    +       *    *    *   u14  u25  u36
 *      *    *    +    +    +    +       *    *   u13  u24  u35  u46
 *      *   a12  a23  a34  a45  a56      *   u12  u23  u34  u45  u56
 *     a11  a22  a33  a44  a55  a66     u11  u22  u33  u44  u55  u66
 *     a21  a32  a43  a54  a65   *      m21  m32  m43  m54  m65   *
 *     a31  a42  a53  a64   *    *      m31  m42  m53  m64   *    *
 *
 *  Array elements marked * are not used by the routine; elements marked
 *  + need not be set on entry, but are required by the routine to store
 *  elements of U because of fill-in resulting from the row interchanges.
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Dgbtrf()

dgbtrf(int, int, int, int, double[], int, int, int[], int, intW)

 public Dgbtrf()

 public static void dgbtrf(int m,
                           int n,
                           int kl,
                           int ku,
                           double ab[],
                           int _ab_offset,
                           int ldab,
                           int ipiv[],
                           int _ipiv_offset,
                           intW info)

All Packages  Class Hierarchy  This Package  Previous  Next  Index