IPARAM2STAGE - 5.2 English - 68552

IPARAM2STAGE program sets problem and machine dependent parameters.

Purpose:

    This program sets problem and machine dependent parameters
    useful for xHETRD_2STAGE, xHETRD_HE2HB, xHETRD_HB2ST,
    xGEBRD_2STAGE, xGEBRD_GE2GB, xGEBRD_GB2BD
    and related subroutines for eigenvalue problems.
    It is called whenever ILAENV is called with 17 <= ISPEC <= 21.
    It is called whenever ILAENV2STAGE is called with 1 <= ISPEC <= 5
    with a direct conversion ISPEC + 16.

Parameters:

• ISPEC – [in]

  ISPEC is integer scalar

  ISPEC specifies which tunable parameter IPARAM2STAGE should return.

  ISPEC=17: the optimal blocksize nb for the reduction to BAND

  ISPEC=18: the optimal blocksize ib for the eigenvectors singular vectors update routine

  ISPEC=19: The length of the array that store the Housholder representation for the second stage Band to Tridiagonal or Bidiagonal

  ISPEC=20: The workspace needed for the routine in input.

  ISPEC=21: For future release.

• NAME – [in]

  NAME is character string

  Name of the calling subroutine

• OPTS – [in]

  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’.

• NI – [in] NI is INTEGER which is the size of the matrix

• NBI – [in]

  NBI is INTEGER which is the used in the reduciton,

  (e.g., the size of the band), needed to compute workspace and LHOUS2.

• IBI – [in] IBI is INTEGER which represent the IB of the reduciton, needed to compute workspace and LHOUS2.

• NXI – [in] NXI is INTEGER needed in the future release.

Returns:

INTEGER Return value of the function.