public class Dlasyf
- 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.
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* DLASYF computes a partial factorization of a real symmetric matrix A
* using the Bunch-Kaufman diagonal pivoting method. The partial
* factorization has the form:
* A = ( I U12 ) ( A11 0 ) ( I 0 ) if UPLO = 'U', or:
* ( 0 U22 ) ( 0 D ) ( U12' U22' )
* A = ( L11 0 ) ( D 0 ) ( L11' L21' ) if UPLO = 'L'
* ( L21 I ) ( 0 A22 ) ( 0 I )
* where the order of D is at most NB. The actual order is returned in
* the argument KB, and is either NB or NB-1, or N if N <= NB.
* DLASYF is an auxiliary routine called by DSYTRF. It uses blocked code
* (calling Level 3 BLAS) to update the submatrix A11 (if UPLO = 'U') or
* A22 (if UPLO = 'L').
* 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.
* NB (input) INTEGER
* The maximum number of columns of the matrix A that should be
* factored. NB should be at least 2 to allow for 2-by-2 pivot
* KB (output) INTEGER
* The number of columns of A that were actually factored.
* KB is either NB-1 or NB, or N if N <= NB.
* A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
* On entry, the symmetric matrix A. If UPLO = 'U', the leading
* n-by-n 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 n-by-n 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, A contains details of the partial factorization.
* 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 UPLO = 'U', only the last KB elements of IPIV are set;
* if UPLO = 'L', only the first KB elements are set.
* If IPIV(k) > 0, then rows and columns k and IPIV(k) were
* interchanged and D(k,k) is a 1-by-1 diagonal block.
* If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, then rows and
* columns k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k)
* is a 2-by-2 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 2-by-2 diagonal block.
* W (workspace) DOUBLE PRECISION array, dimension (LDW,NB)
* LDW (input) INTEGER
* The leading dimension of the array W. LDW >= max(1,N).
* INFO (output) INTEGER
* = 0: successful exit
* > 0: if INFO = k, D(k,k) is exactly zero. The factorization
* has been completed, but the block diagonal matrix D is
* exactly singular.
* .. Parameters ..
|Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public static void dlasyf(java.lang.String uplo,