GSP
Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Support
Contact Us
Online Help
Handbooks
Domain Status
Man Pages

FAQ
Virtual Servers
Pricing
Billing
Technical

Network
Facilities
Connectivity
Topology Map

Miscellaneous
Server Agreement
Year 2038
Credits
 

USA Flag

 

 

Man Pages
zlaqr1.f(3) LAPACK zlaqr1.f(3)

zlaqr1.f -


subroutine zlaqr1 (N, H, LDH, S1, S2, V)
 
ZLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.

ZLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.
Purpose:
      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.
Parameters:
N
          N is integer
              Order of the matrix H. N must be either 2 or 3.
H
          H is COMPLEX*16 array of dimension (LDH,N)
              The 2-by-2 or 3-by-3 matrix H in (*).
LDH
          LDH is integer
              The leading dimension of H as declared in
              the calling procedure.  LDH.GE.N
S1
          S1 is COMPLEX*16
S2
          S2 is COMPLEX*16
S1 and S2 are the shifts defining K in (*) above.
V
          V is COMPLEX*16 array of dimension N
              A scalar multiple of the first column of the
              matrix K in (*).
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Contributors:
Karen Braman and Ralph Byers, Department of Mathematics, University of Kansas, USA
Definition at line 108 of file zlaqr1.f.

Generated automatically by Doxygen for LAPACK from the source code.
Sat Nov 16 2013 Version 3.4.2

Search for    or go to Top of page |  Section 3 |  Main Index

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.