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
ZLAMSH(l) ) ZLAMSH(l)

ZLAMSH - send multiple shifts through a small (single node) matrix to see how consecutive small subdiagonal elements are modified by subsequent shifts in an effort to maximize the number of bulges that can be sent through

SUBROUTINE ZLAMSH(
S, LDS, NBULGE, JBLK, H, LDH, N, ULP )
INTEGER JBLK, LDH, LDS, N, NBULGE DOUBLE PRECISION ULP COMPLEX*16 H( LDH, * ), S( LDS, * )

ZLAMSH sends multiple shifts through a small (single node) matrix to see how consecutive small subdiagonal elements are modified by subsequent shifts in an effort to maximize the number of bulges that can be sent through. ZLAMSH should only be called when there are multiple shifts/bulges
(NBULGE > 1) and the first shift is starting in the middle of an
unreduced Hessenberg matrix because of two or more consecutive
small subdiagonal elements.
 

S (local input/output) COMPLEX*16 array, ( LDS,* )
On entry, the matrix of shifts. Only the 2x2 diagonal of S is referenced. It is assumed that S has JBLK double shifts (size 2). On exit, the data is rearranged in the best order for applying.
LDS (local input) INTEGER
On entry, the leading dimension of S. Unchanged on exit. 1 < NBULGE <= JBLK <= LDS/2
NBULGE (local input/output) INTEGER
On entry, the number of bulges to send through H ( >1 ). NBULGE should be less than the maximum determined (JBLK). 1 < NBULGE <= JBLK <= LDS/2 On exit, the maximum number of bulges that can be sent through.
JBLK (local input) INTEGER
On entry, the number of shifts determined for S. Unchanged on exit.
H (local input/output) COMPLEX*16 array ( LDH,N )
On entry, the local matrix to apply the shifts on. H should be aligned so that the starting row is 2. On exit, the data is destroyed.
LDH (local input) INTEGER
On entry, the leading dimension of H. Unchanged on exit.
N (local input) INTEGER
On entry, the size of H. If all the bulges are expected to go through, N should be at least 4*NBULGE+2. Otherwise, NBULGE may be reduced by this routine.
ULP (local input) DOUBLE PRECISION
On entry, machine precision Unchanged on exit.

Implemented by: M. Fahey, May 28, 1999
 
13 August 2001 ScaLAPACK version 1.7

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

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