.TH "zlaqr1.f" 3 "Wed Oct 15 2014" "Version 3.4.2" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
zlaqr1.f \- 
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBzlaqr1\fP (N, H, LDH, S1, S2, V)"
.br
.RI "\fI\fBZLAQR1\fP sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts\&. \fP"
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine zlaqr1 (integerN, complex*16, dimension( ldh, * )H, integerLDH, complex*16S1, complex*16S2, complex*16, dimension( * )V)"

.PP
\fBZLAQR1\fP sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts\&.  
.PP
\fBPurpose: \fP
.RS 4

.PP
.nf
      Given a 2-by-2 or 3-by-3 matrix H, ZLAQR1 sets v to a
      scalar multiple of the first column of the product

      (*)  K = (H - s1*I)*(H - s2*I)

      scaling to avoid overflows and most underflows.

      This is useful for starting double implicit shift bulges
      in the QR algorithm.
.fi
.PP
 
.RE
.PP
\fBParameters:\fP
.RS 4
\fIN\fP 
.PP
.nf
          N is integer
              Order of the matrix H. N must be either 2 or 3.
.fi
.PP
.br
\fIH\fP 
.PP
.nf
          H is COMPLEX*16 array of dimension (LDH,N)
              The 2-by-2 or 3-by-3 matrix H in (*).
.fi
.PP
.br
\fILDH\fP 
.PP
.nf
          LDH is integer
              The leading dimension of H as declared in
              the calling procedure.  LDH.GE.N
.fi
.PP
.br
\fIS1\fP 
.PP
.nf
          S1 is COMPLEX*16
.fi
.PP
.br
\fIS2\fP 
.PP
.nf
          S2 is COMPLEX*16

          S1 and S2 are the shifts defining K in (*) above.
.fi
.PP
.br
\fIV\fP 
.PP
.nf
          V is COMPLEX*16 array of dimension N
              A scalar multiple of the first column of the
              matrix K in (*).
.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
\fBDate:\fP
.RS 4
September 2012 
.RE
.PP
\fBContributors: \fP
.RS 4
Karen Braman and Ralph Byers, Department of Mathematics, University of Kansas, USA 
.RE
.PP

.PP
Definition at line 108 of file zlaqr1\&.f\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.