# iparam2stage - Man Page

iparam2stage: sets parameters for 2-stage eig

## Synopsis

### Functions

integer function iparam2stage (ispec, name, opts, ni, nbi, ibi, nxi)
IPARAM2STAGE

## Function Documentation

### integer function iparam2stage (integer ispec, character*( * ) name, character*( * ) opts, integer ni, integer nbi, integer ibi, integer nxi)

IPARAM2STAGE

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

```          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

```          NAME is character string
Name of the calling subroutine```

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'.```

NI

`          NI is INTEGER which is the size of the matrix`

NBI

```          NBI is INTEGER which is the used in the reduction,
(e.g., the size of the band), needed to compute workspace
and LHOUS2.```

IBI

```          IBI is INTEGER which represent the IB of the reduction,
needed to compute workspace and LHOUS2.```

NXI

`          NXI is INTEGER needed in the future release.`
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Further Details:

```  Implemented by Azzam Haidar.

All detail are available on technical report, SC11, SC13 papers.

Azzam Haidar, Hatem Ltaief, and Jack Dongarra.
Parallel reduction to condensed forms for symmetric eigenvalue problems
using aggregated fine-grained and memory-aware kernels. In Proceedings
of 2011 International Conference for High Performance Computing,
Networking, Storage and Analysis (SC '11), New York, NY, USA,
Article 8 , 11 pages.
http://doi.acm.org/10.1145/2063384.2063394

A. Haidar, J. Kurzak, P. Luszczek, 2013.
An improved parallel singular value algorithm and its implementation
for multicore hardware, In Proceedings of 2013 International Conference
for High Performance Computing, Networking, Storage and Analysis (SC '13).
Article 90, 12 pages.
http://doi.acm.org/10.1145/2503210.2503292

A. Haidar, R. Solca, S. Tomov, T. Schulthess and J. Dongarra.
A novel hybrid CPU-GPU generalized eigensolver for electronic structure
calculations based on fine-grained memory aware tasks.
International Journal of High Performance Computing Applications.
Volume 28 Issue 2, Pages 196-209, May 2014.
http://hpc.sagepub.com/content/28/2/196```

Definition at line 153 of file iparam2stage.F.

## Author

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## Info

Tue Nov 28 2023 12:08:43 Version 3.12.0 LAPACK