.TH "SRC/slarra.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/slarra.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBslarra\fP (n, d, e, e2, spltol, tnrm, nsplit, isplit, info)"
.br
.RI "\fBSLARRA\fP computes the splitting points with the specified threshold\&. "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine slarra (integer n, real, dimension( * ) d, real, dimension( * ) e, real, dimension( * ) e2, real spltol, real tnrm, integer nsplit, integer, dimension( * ) isplit, integer info)"

.PP
\fBSLARRA\fP computes the splitting points with the specified threshold\&.  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> Compute the splitting points with threshold SPLTOL\&.
!> SLARRA sets any  off-diagonal elements to zero\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIN\fP 
.PP
.nf
!>          N is INTEGER
!>          The order of the matrix\&. N > 0\&.
!> 
.fi
.PP
.br
\fID\fP 
.PP
.nf
!>          D is REAL array, dimension (N)
!>          On entry, the N diagonal elements of the tridiagonal
!>          matrix T\&.
!> 
.fi
.PP
.br
\fIE\fP 
.PP
.nf
!>          E is REAL array, dimension (N)
!>          On entry, the first (N-1) entries contain the subdiagonal
!>          elements of the tridiagonal matrix T; E(N) need not be set\&.
!>          On exit, the entries E( ISPLIT( I ) ), 1 <= I <= NSPLIT,
!>          are set to zero, the other entries of E are untouched\&.
!> 
.fi
.PP
.br
\fIE2\fP 
.PP
.nf
!>          E2 is REAL array, dimension (N)
!>          On entry, the first (N-1) entries contain the SQUARES of the
!>          subdiagonal elements of the tridiagonal matrix T;
!>          E2(N) need not be set\&.
!>          On exit, the entries E2( ISPLIT( I ) ),
!>          1 <= I <= NSPLIT, have been set to zero
!> 
.fi
.PP
.br
\fISPLTOL\fP 
.PP
.nf
!>          SPLTOL is REAL
!>          The threshold for splitting\&. Two criteria can be used:
!>          SPLTOL<0 : criterion based on absolute off-diagonal value
!>          SPLTOL>0 : criterion that preserves relative accuracy
!> 
.fi
.PP
.br
\fITNRM\fP 
.PP
.nf
!>          TNRM is REAL
!>          The norm of the matrix\&.
!> 
.fi
.PP
.br
\fINSPLIT\fP 
.PP
.nf
!>          NSPLIT is INTEGER
!>          The number of blocks T splits into\&. 1 <= NSPLIT <= N\&.
!> 
.fi
.PP
.br
\fIISPLIT\fP 
.PP
.nf
!>          ISPLIT is INTEGER array, dimension (N)
!>          The splitting points, at which T breaks up into blocks\&.
!>          The first block consists of rows/columns 1 to ISPLIT(1),
!>          the second of rows/columns ISPLIT(1)+1 through ISPLIT(2),
!>          etc\&., and the NSPLIT-th consists of rows/columns
!>          ISPLIT(NSPLIT-1)+1 through ISPLIT(NSPLIT)=N\&.
!> 
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
!>          INFO is INTEGER
!>          = 0:  successful exit
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

.PP
Univ\&. of California Berkeley 

.PP
Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 
.RE
.PP
\fBContributors:\fP
.RS 4
Beresford Parlett, University of California, Berkeley, USA 
.br
Jim Demmel, University of California, Berkeley, USA 
.br
Inderjit Dhillon, University of Texas, Austin, USA 
.br
Osni Marques, LBNL/NERSC, USA 
.br
Christof Voemel, University of California, Berkeley, USA 
.RE
.PP

.PP
Definition at line \fB134\fP of file \fBslarra\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.