ilaenv2stage()

integer function ilaenv2stage	(	integer	ispec,
		character*( * )	name,
		character*( * )	opts,
		integer	n1,
		integer	n2,
		integer	n3,
		integer	n4 )

ILAENV2STAGE

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Purpose:

!>
!> ILAENV2STAGE is called from the LAPACK routines to choose problem-dependent
!> parameters for the local environment.  See ISPEC for a description of
!> the parameters.
!> It sets problem and machine dependent parameters useful for *_2STAGE and
!> related subroutines.
!>
!> ILAENV2STAGE returns an INTEGER
!> if ILAENV2STAGE >= 0: ILAENV2STAGE returns the value of the parameter
!>                       specified by ISPEC
!> if ILAENV2STAGE < 0:  if ILAENV2STAGE = -k, the k-th argument had an
!>                       illegal value.
!>
!> This version provides a set of parameters which should give good,
!> but not optimal, performance on many of the currently available
!> computers for the 2-stage solvers. Users are encouraged to modify this
!> subroutine to set the tuning parameters for their particular machine using
!> the option and problem size information in the arguments.
!>
!> This routine will not function correctly if it is converted to all
!> lower case.  Converting it to all upper case is allowed.
!> 

Parameters

[in]	ISPEC	!> ISPEC is INTEGER !> Specifies the parameter to be returned as the value of !> ILAENV2STAGE. !> = 1: the optimal blocksize nb for the reduction to BAND !> !> = 2: the optimal blocksize ib for the eigenvectors !> singular vectors update routine !> !> = 3: The length of the array that store the Housholder !> representation for the second stage !> Band to Tridiagonal or Bidiagonal !> !> = 4: The workspace needed for the routine in input. !> !> = 5: For future release. !>
[in]	NAME	!> NAME is CHARACTER*(*) !> The name of the calling subroutine, in either upper case or !> lower case. !>
[in]	OPTS	!> OPTS is CHARACTER*(*) !> The character options to the subroutine NAME, concatenated !> into a single character string. For example, UPLO = 'U', !> TRANS = 'T', and DIAG = 'N' for a triangular routine would !> be specified as OPTS = 'UTN'. !>
[in]	N1	!> N1 is INTEGER !>
[in]	N2	!> N2 is INTEGER !>
[in]	N3	!> N3 is INTEGER !>
[in]	N4	!> N4 is INTEGER !> Problem dimensions for the subroutine NAME; these may not all !> be required. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Nick R. Papior

Further Details:

!>
!>  The following conventions have been used when calling ILAENV2STAGE
!> from the LAPACK routines:
!>  1)  OPTS is a concatenation of all of the character options to
!>      subroutine NAME, in the same order that they appear in the
!>      argument list for NAME, even if they are not used in determining
!>      the value of the parameter specified by ISPEC.
!>  2)  The problem dimensions N1, N2, N3, N4 are specified in the order
!>      that they appear in the argument list for NAME.  N1 is used
!>      first, N2 second, and so on, and unused problem dimensions are
!>      passed a value of -1.
!>  3)  The parameter value returned by ILAENV2STAGE is checked for validity in
!>      the calling subroutine.
!>
!> 

Definition at line 146 of file ilaenv2stage.f.

*
*  -- LAPACK auxiliary routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     July 2017
*
*     .. Scalar Arguments ..
      CHARACTER*( * )    NAME, OPTS
      INTEGER            ISPEC, N1, N2, N3, N4
*     ..
*
*  =====================================================================
*     ..
*     .. Local Scalars ..
      INTEGER            IISPEC
*     ..
*     .. External Functions ..
      INTEGER            IPARAM2STAGE
      EXTERNAL           iparam2stage
*     ..
*     .. Executable Statements ..
*
      GO TO ( 10, 10, 10, 10, 10 )ispec
*
*     Invalid value for ISPEC
*
      ilaenv2stage = -1
      RETURN
*
   10 CONTINUE
*
*     2stage eigenvalues and SVD or related subroutines.
*
      iispec = 16 + ispec
      ilaenv2stage = iparam2stage( iispec, name, opts,
     $                             n1, n2, n3, n4 )
      RETURN
*
*     End of ILAENV2STAGE
*

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