Unix/Linux Go Back    


CentOS 7.0 - man page for sstedc (centos section 3)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


sstedc.f(3)				      LAPACK				      sstedc.f(3)

NAME
       sstedc.f -

SYNOPSIS
   Functions/Subroutines
       subroutine sstedc (COMPZ, N, D, E, Z, LDZ, WORK, LWORK, IWORK, LIWORK, INFO)
	   SSTEBZ

Function/Subroutine Documentation
   subroutine sstedc (characterCOMPZ, integerN, real, dimension( * )D, real, dimension( * )E,
       real, dimension( ldz, * )Z, integerLDZ, real, dimension( * )WORK, integerLWORK, integer,
       dimension( * )IWORK, integerLIWORK, integerINFO)
       SSTEBZ

       Purpose:

	    SSTEDC computes all eigenvalues and, optionally, eigenvectors of a
	    symmetric tridiagonal matrix using the divide and conquer method.
	    The eigenvectors of a full or band real symmetric matrix can also be
	    found if SSYTRD or SSPTRD or SSBTRD has been used to reduce this
	    matrix to tridiagonal form.

	    This code makes very mild assumptions about floating point
	    arithmetic. It will work on machines with a guard digit in
	    add/subtract, or on those binary machines without guard digits
	    which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2.
	    It could conceivably fail on hexadecimal or decimal machines
	    without guard digits, but we know of none.	See SLAED3 for details.

       Parameters:
	   COMPZ

		     COMPZ is CHARACTER*1
		     = 'N':  Compute eigenvalues only.
		     = 'I':  Compute eigenvectors of tridiagonal matrix also.
		     = 'V':  Compute eigenvectors of original dense symmetric
			     matrix also.  On entry, Z contains the orthogonal
			     matrix used to reduce the original matrix to
			     tridiagonal form.

	   N

		     N is INTEGER
		     The dimension of the symmetric tridiagonal matrix.  N >= 0.

	   D

		     D is REAL array, dimension (N)
		     On entry, the diagonal elements of the tridiagonal matrix.
		     On exit, if INFO = 0, the eigenvalues in ascending order.

	   E

		     E is REAL array, dimension (N-1)
		     On entry, the subdiagonal elements of the tridiagonal matrix.
		     On exit, E has been destroyed.

	   Z

		     Z is REAL array, dimension (LDZ,N)
		     On entry, if COMPZ = 'V', then Z contains the orthogonal
		     matrix used in the reduction to tridiagonal form.
		     On exit, if INFO = 0, then if COMPZ = 'V', Z contains the
		     orthonormal eigenvectors of the original symmetric matrix,
		     and if COMPZ = 'I', Z contains the orthonormal eigenvectors
		     of the symmetric tridiagonal matrix.
		     If  COMPZ = 'N', then Z is not referenced.

	   LDZ

		     LDZ is INTEGER
		     The leading dimension of the array Z.  LDZ >= 1.
		     If eigenvectors are desired, then LDZ >= max(1,N).

	   WORK

		     WORK is REAL array, dimension (MAX(1,LWORK))
		     On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

	   LWORK

		     LWORK is INTEGER
		     The dimension of the array WORK.
		     If COMPZ = 'N' or N <= 1 then LWORK must be at least 1.
		     If COMPZ = 'V' and N > 1 then LWORK must be at least
				    ( 1 + 3*N + 2*N*lg N + 4*N**2 ),
				    where lg( N ) = smallest integer k such
				    that 2**k >= N.
		     If COMPZ = 'I' and N > 1 then LWORK must be at least
				    ( 1 + 4*N + N**2 ).
		     Note that for COMPZ = 'I' or 'V', then if N is less than or
		     equal to the minimum divide size, usually 25, then LWORK need
		     only be max(1,2*(N-1)).

		     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.

	   IWORK

		     IWORK is INTEGER array, dimension (MAX(1,LIWORK))
		     On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK.

	   LIWORK

		     LIWORK is INTEGER
		     The dimension of the array IWORK.
		     If COMPZ = 'N' or N <= 1 then LIWORK must be at least 1.
		     If COMPZ = 'V' and N > 1 then LIWORK must be at least
				    ( 6 + 6*N + 5*N*lg N ).
		     If COMPZ = 'I' and N > 1 then LIWORK must be at least
				    ( 3 + 5*N ).
		     Note that for COMPZ = 'I' or 'V', then if N is less than or
		     equal to the minimum divide size, usually 25, then LIWORK
		     need only be 1.

		     If LIWORK = -1, then a workspace query is assumed; the
		     routine only calculates the optimal size of the IWORK array,
		     returns this value as the first entry of the IWORK array, and
		     no error message related to LIWORK is issued by XERBLA.

	   INFO

		     INFO is INTEGER
		     = 0:  successful exit.
		     < 0:  if INFO = -i, the i-th argument had an illegal value.
		     > 0:  The algorithm failed to compute an eigenvalue while
			   working on the submatrix lying in rows and columns
			   INFO/(N+1) through mod(INFO,N+1).

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Contributors:
	   Jeff Rutter, Computer Science Division, University of California at Berkeley, USA
	    Modified by Francoise Tisseur, University of Tennessee

       Definition at line 188 of file sstedc.f.

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

Version 3.4.2				 Tue Sep 25 2012			      sstedc.f(3)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 05:46 PM.