chetf2.f man page on RedHat

Man page or keyword search:  
man Server   29550 pages
apropos Keyword Search (all sections)
Output format
RedHat logo
[printable version]

chetf2.f(3)			    LAPACK			   chetf2.f(3)

NAME
       chetf2.f -

SYNOPSIS
   Functions/Subroutines
       subroutine chetf2 (UPLO, N, A, LDA, IPIV, INFO)
	   CHETF2 computes the factorization of a complex Hermitian matrix,
	   using the diagonal pivoting method (unblocked algorithm).

Function/Subroutine Documentation
   subroutine chetf2 (characterUPLO, integerN, complex, dimension( lda, * )A,
       integerLDA, integer, dimension( * )IPIV, integerINFO)
       CHETF2 computes the factorization of a complex Hermitian matrix, using
       the diagonal pivoting method (unblocked algorithm).

       Purpose:

	    CHETF2 computes the factorization of a complex Hermitian matrix A
	    using the Bunch-Kaufman diagonal pivoting method:

	       A = U*D*U**H  or	 A = L*D*L**H

	    where U (or L) is a product of permutation and unit upper (lower)
	    triangular matrices, U**H is the conjugate transpose of U, and D is
	    Hermitian and block diagonal with 1-by-1 and 2-by-2 diagonal blocks.

	    This is the unblocked version of the algorithm, calling Level 2 BLAS.

       Parameters:
	   UPLO

		     UPLO is CHARACTER*1
		     Specifies whether the upper or lower triangular part of the
		     Hermitian matrix A is stored:
		     = 'U':  Upper triangular
		     = 'L':  Lower triangular

	   N

		     N is INTEGER
		     The order of the matrix A.	 N >= 0.

	   A

		     A is COMPLEX array, dimension (LDA,N)
		     On entry, the Hermitian 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, the block diagonal matrix D and the multipliers used
		     to obtain the factor U or L (see below for further details).

	   LDA

		     LDA is INTEGER
		     The leading dimension of the array A.  LDA >= max(1,N).

	   IPIV

		     IPIV is 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 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.

	   INFO

		     INFO is INTEGER
		     = 0: successful exit
		     < 0: if INFO = -k, the k-th 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.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Further Details:

	     09-29-06 - patch from
	       Bobby Cheng, MathWorks

	       Replace l.210 and l.392
		    IF( MAX( ABSAKK, COLMAX ).EQ.ZERO ) THEN
	       by
		    IF( (MAX( ABSAKK, COLMAX ).EQ.ZERO) .OR. SISNAN(ABSAKK) ) THEN

	     01-01-96 - Based on modifications by
	       J. Lewis, Boeing Computer Services Company
	       A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

	     If UPLO = 'U', then A = U*D*U**H, where
		U = P(n)*U(n)* ... <em>P(k)U(k)</em> ...,
	     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 1-by-1
	     and 2-by-2 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	  )   k-s
		U(k) =	(   0	 I    0	  )   s
			(   0	 0    I	  )   n-k
			   k-s	 s   n-k

	     If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k-1,k).
	     If s = 2, the upper triangle of D(k) overwrites A(k-1,k-1), A(k-1,k),
	     and A(k,k), and v overwrites A(1:k-2,k-1:k).

	     If UPLO = 'L', then A = L*D*L**H, where
		L = P(1)*L(1)* ... <em>P(k)*L(k)</em> ...,
	     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 1-by-1
	     and 2-by-2 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   )  k-1
		L(k) =	(   0	 I     0   )  s
			(   0	 v     I   )  n-k-s+1
			   k-1	 s  n-k-s+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).

       Definition at line 178 of file chetf2.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2			Tue Sep 25 2012			   chetf2.f(3)
[top]

List of man pages available for RedHat

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net