LAPACK  3.10.1
LAPACK: Linear Algebra PACKage

◆ ilaenv2stage()

integer function ilaenv2stage ( integer  ISPEC,
character*( * )  NAME,
character*( * )  OPTS,
integer  N1,
integer  N2,
integer  N3,
integer  N4 


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 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.

 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.
          ISPEC is INTEGER
          Specifies the parameter to be returned as the value of
          = 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.
          NAME is CHARACTER*(*)
          The name of the calling subroutine, in either upper case or
          lower case.
          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'.
          N1 is INTEGER
          N2 is INTEGER
          N3 is INTEGER
          N4 is INTEGER
          Problem dimensions for the subroutine NAME; these may not all
          be required.
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 148 of file ilaenv2stage.f.

149 *
150 * -- LAPACK auxiliary routine --
151 * -- LAPACK is a software package provided by Univ. of Tennessee, --
152 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
153 * July 2017
154 *
155 * .. Scalar Arguments ..
157  INTEGER ISPEC, N1, N2, N3, N4
158 * ..
159 *
160 * =====================================================================
161 * ..
162 * .. Local Scalars ..
164 * ..
165 * .. External Functions ..
167  EXTERNAL iparam2stage
168 * ..
169 * .. Executable Statements ..
170 *
171  GO TO ( 10, 10, 10, 10, 10 )ispec
172 *
173 * Invalid value for ISPEC
174 *
175  ilaenv2stage = -1
177 *
178  10 CONTINUE
179 *
180 * 2stage eigenvalues and SVD or related subroutines.
181 *
182  iispec = 16 + ispec
183  ilaenv2stage = iparam2stage( iispec, name, opts,
184  $ n1, n2, n3, n4 )
186 *
187 * End of ILAENV2STAGE
188 *
integer function ilaenv2stage(ISPEC, NAME, OPTS, N1, N2, N3, N4)
Definition: ilaenv2stage.f:149
integer function iparam2stage(ISPEC, NAME, OPTS, NI, NBI, IBI, NXI)
Definition: iparam2stage.F:155
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