org.netlib.lapack
Class DSYTF2
java.lang.Object
org.netlib.lapack.DSYTF2
public class DSYTF2
 extends java.lang.Object
DSYTF2 is a simplified interface to the JLAPACK routine dsytf2.
This interface converts Javastyle 2D rowmajor arrays into
the 1D columnmajor linearized arrays expected by the lower
level JLAPACK routines. Using this interface also allows you
to omit offset and leading dimension arguments. However, because
of these conversions, these routines will be slower than the low
level ones. Following is the description from the original Fortran
source. Contact seymour@cs.utk.edu with any questions.
* ..
*
* Purpose
* =======
*
* DSYTF2 computes the factorization of a real symmetric matrix A using
* the BunchKaufman diagonal pivoting method:
*
* A = U*D*U' or A = L*D*L'
*
* where U (or L) is a product of permutation and unit upper (lower)
* triangular matrices, U' is the transpose of U, and D is symmetric and
* block diagonal with 1by1 and 2by2 diagonal blocks.
*
* This is the unblocked version of the algorithm, calling Level 2 BLAS.
*
* Arguments
* =========
*
* UPLO (input) CHARACTER*1
* Specifies whether the upper or lower triangular part of the
* symmetric matrix A is stored:
* = 'U': Upper triangular
* = 'L': Lower triangular
*
* N (input) INTEGER
* The order of the matrix A. N >= 0.
*
* A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
* On entry, the symmetric matrix A. If UPLO = 'U', the leading
* nbyn upper triangular part of A contains the upper
* triangular part of the matrix A, and the strictly lower
* triangular part of A is not referenced. If UPLO = 'L', the
* leading nbyn lower triangular part of A contains the lower
* triangular part of the matrix A, and the strictly upper
* triangular part of A is not referenced.
*
* On exit, the block diagonal matrix D and the multipliers used
* to obtain the factor U or L (see below for further details).
*
* LDA (input) INTEGER
* The leading dimension of the array A. LDA >= max(1,N).
*
* IPIV (output) INTEGER array, dimension (N)
* Details of the interchanges and the block structure of D.
* If IPIV(k) > 0, then rows and columns k and IPIV(k) were
* interchanged and D(k,k) is a 1by1 diagonal block.
* If UPLO = 'U' and IPIV(k) = IPIV(k1) < 0, then rows and
* columns k1 and IPIV(k) were interchanged and D(k1:k,k1:k)
* is a 2by2 diagonal block. If UPLO = 'L' and IPIV(k) =
* IPIV(k+1) < 0, then rows and columns k+1 and IPIV(k) were
* interchanged and D(k:k+1,k:k+1) is a 2by2 diagonal block.
*
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if INFO = k, the kth argument had an illegal value
* > 0: if INFO = k, D(k,k) is exactly zero. The factorization
* has been completed, but the block diagonal matrix D is
* exactly singular, and division by zero will occur if it
* is used to solve a system of equations.
*
* Further Details
* ===============
*
* 196  Based on modifications by J. Lewis, Boeing Computer Services
* Company
*
* If UPLO = 'U', then A = U*D*U', where
* U = P(n)*U(n)* ... *P(k)U(k)* ...,
* i.e., U is a product of terms P(k)*U(k), where k decreases from n to
* 1 in steps of 1 or 2, and D is a block diagonal matrix with 1by1
* and 2by2 diagonal blocks D(k). P(k) is a permutation matrix as
* defined by IPIV(k), and U(k) is a unit upper triangular matrix, such
* that if the diagonal block D(k) is of order s (s = 1 or 2), then
*
* ( I v 0 ) ks
* U(k) = ( 0 I 0 ) s
* ( 0 0 I ) nk
* ks s nk
*
* If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k1,k).
* If s = 2, the upper triangle of D(k) overwrites A(k1,k1), A(k1,k),
* and A(k,k), and v overwrites A(1:k2,k1:k).
*
* If UPLO = 'L', then A = L*D*L', where
* L = P(1)*L(1)* ... *P(k)*L(k)* ...,
* i.e., L is a product of terms P(k)*L(k), where k increases from 1 to
* n in steps of 1 or 2, and D is a block diagonal matrix with 1by1
* and 2by2 diagonal blocks D(k). P(k) is a permutation matrix as
* defined by IPIV(k), and L(k) is a unit lower triangular matrix, such
* that if the diagonal block D(k) is of order s (s = 1 or 2), then
*
* ( I 0 0 ) k1
* L(k) = ( 0 I 0 ) s
* ( 0 v I ) nks+1
* k1 s nks+1
*
* If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k).
* If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k),
* and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1).
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
DSYTF2(java.lang.String uplo,
int n,
double[][] a,
int[] ipiv,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
DSYTF2
public DSYTF2()
DSYTF2
public static void DSYTF2(java.lang.String uplo,
int n,
double[][] a,
int[] ipiv,
intW info)