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sspevd.f(3)				      LAPACK				      sspevd.f(3)

NAME
       sspevd.f -

SYNOPSIS
   Functions/Subroutines
       subroutine sspevd (JOBZ, UPLO, N, AP, W, Z, LDZ, WORK, LWORK, IWORK, LIWORK, INFO)
	    SSPEVD computes the eigenvalues and, optionally, the left and/or right eigenvectors
	   for OTHER matrices

Function/Subroutine Documentation
   subroutine sspevd (characterJOBZ, characterUPLO, integerN, real, dimension( * )AP, real,
       dimension( * )W, real, dimension( ldz, * )Z, integerLDZ, real, dimension( * )WORK,
       integerLWORK, integer, dimension( * )IWORK, integerLIWORK, integerINFO)
	SSPEVD computes the eigenvalues and, optionally, the left and/or right eigenvectors for
       OTHER matrices

       Purpose:

	    SSPEVD computes all the eigenvalues and, optionally, eigenvectors
	    of a real symmetric matrix A in packed storage. If eigenvectors are
	    desired, it uses a divide and conquer algorithm.

	    The divide and conquer algorithm 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.

       Parameters:
	   JOBZ

		     JOBZ is CHARACTER*1
		     = 'N':  Compute eigenvalues only;
		     = 'V':  Compute eigenvalues and eigenvectors.

	   UPLO

		     UPLO is CHARACTER*1
		     = 'U':  Upper triangle of A is stored;
		     = 'L':  Lower triangle of A is stored.

	   N

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

	   AP

		     AP is REAL array, dimension (N*(N+1)/2)
		     On entry, the upper or lower triangle of the symmetric matrix
		     A, packed columnwise in a linear array.  The j-th column of A
		     is stored in the array AP as follows:
		     if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
		     if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.

		     On exit, AP is overwritten by values generated during the
		     reduction to tridiagonal form.  If UPLO = 'U', the diagonal
		     and first superdiagonal of the tridiagonal matrix T overwrite
		     the corresponding elements of A, and if UPLO = 'L', the
		     diagonal and first subdiagonal of T overwrite the
		     corresponding elements of A.

	   W

		     W is REAL array, dimension (N)
		     If INFO = 0, the eigenvalues in ascending order.

	   Z

		     Z is REAL array, dimension (LDZ, N)
		     If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
		     eigenvectors of the matrix A, with the i-th column of Z
		     holding the eigenvector associated with W(i).
		     If JOBZ = 'N', then Z is not referenced.

	   LDZ

		     LDZ is INTEGER
		     The leading dimension of the array Z.  LDZ >= 1, and if
		     JOBZ = 'V', LDZ >= max(1,N).

	   WORK

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

	   LWORK

		     LWORK is INTEGER
		     The dimension of the array WORK.
		     If N <= 1, 	      LWORK must be at least 1.
		     If JOBZ = 'N' and N > 1, LWORK must be at least 2*N.
		     If JOBZ = 'V' and N > 1, LWORK must be at least
							    1 + 6*N + N**2.

		     If LWORK = -1, then a workspace query is assumed; the routine
		     only calculates the required sizes of the WORK and IWORK
		     arrays, returns these values as the first entries of the WORK
		     and IWORK arrays, and no error message related to LWORK or
		     LIWORK is issued by XERBLA.

	   IWORK

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

	   LIWORK

		     LIWORK is INTEGER
		     The dimension of the array IWORK.
		     If JOBZ  = 'N' or N <= 1, LIWORK must be at least 1.
		     If JOBZ  = 'V' and N > 1, LIWORK must be at least 3 + 5*N.

		     If LIWORK = -1, then a workspace query is assumed; the
		     routine only calculates the required sizes of the WORK and
		     IWORK arrays, returns these values as the first entries of
		     the WORK and IWORK arrays, and no error message related to
		     LWORK or 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:  if INFO = i, the algorithm failed to converge; i
			   off-diagonal elements of an intermediate tridiagonal
			   form did not converge to zero.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 178 of file sspevd.f.

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

Version 3.4.2				 Tue Sep 25 2012			      sspevd.f(3)
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