# iparam2stage - Man Page

iparam2stage: sets parameters for 2-stage eig

## Synopsis

### Functions

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

## Detailed Description

## 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

Univ. of Colorado Denver

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). Denver, Colorado, USA, 2013. 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