.TH "ilaenv2stage" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
ilaenv2stage \- ilaenv2stage: tuning parameters for 2-stage eig
.SH SYNOPSIS
.br
.PP
.SS "Functions"

.in +1c
.ti -1c
.RI "integer function \fBilaenv2stage\fP (ispec, name, opts, n1, n2, n3, n4)"
.br
.RI "\fBILAENV2STAGE\fP "
.in -1c
.SH "Detailed Description"
.PP 

.SH "Function Documentation"
.PP 
.SS "integer function ilaenv2stage (integer ispec, character*( * ) name, character*( * ) opts, integer n1, integer n2, integer n3, integer n4)"

.PP
\fBILAENV2STAGE\fP  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> 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\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIISPEC\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fINAME\fP 
.PP
.nf
!>          NAME is CHARACTER*(*)
!>          The name of the calling subroutine, in either upper case or
!>          lower case\&.
!> 
.fi
.PP
.br
\fIOPTS\fP 
.PP
.nf
!>          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'\&.
!> 
.fi
.PP
.br
\fIN1\fP 
.PP
.nf
!>          N1 is INTEGER
!> 
.fi
.PP
.br
\fIN2\fP 
.PP
.nf
!>          N2 is INTEGER
!> 
.fi
.PP
.br
\fIN3\fP 
.PP
.nf
!>          N3 is INTEGER
!> 
.fi
.PP
.br
\fIN4\fP 
.PP
.nf
!>          N4 is INTEGER
!>          Problem dimensions for the subroutine NAME; these may not all
!>          be required\&.
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

.PP
Univ\&. of California Berkeley 

.PP
Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 

.PP
Nick R\&. Papior 
.RE
.PP
\fBFurther Details:\fP
.RS 4

.PP
.nf
!>
!>  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\&.
!>
!> 
.fi
.PP
 
.RE
.PP

.PP
Definition at line \fB148\fP of file \fBilaenv2stage\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.