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
HPL_pdrpanllT(3) HPL Library Functions HPL_pdrpanllT(3)

HPL_pdrpanllT - Left-looking recursive panel factorization.

#include "hpl.h"

void HPL_pdrpanllT( HPL_T_panel * PANEL, const int M, const int N, const int ICOFF, double * WORK );

HPL_pdrpanllT recursively factorizes a panel of columns using the recursive Left-looking variant of the one-dimensional algorithm. The lower triangular N0-by-N0 upper block of the panel is stored in transpose form.

Bi-directional exchange is used to perform the swap::broadcast operations at once for one column in the panel. This results in a lower number of slightly larger messages than usual. On P processes and assuming bi-directional links, the running time of this function can be approximated by (when N is equal to N0):

N0 * log_2( P ) * ( lat + ( 2*N0 + 4 ) / bdwth ) + N0^2 * ( M - N0/3 ) * gam2-3

where M is the local number of rows of the panel, lat and bdwth are the latency and bandwidth of the network for double precision real words, and gam2-3 is an estimate of the Level 2 and Level 3 BLAS rate of execution. The recursive algorithm allows indeed to almost achieve Level 3 BLAS performance in the panel factorization. On a large number of modern machines, this operation is however latency bound, meaning that its cost can be estimated by only the latency portion N0 * log_2(P) * lat. Mono-directional links will double this communication cost.

PANEL (local input/output) HPL_T_panel *
On entry, PANEL points to the data structure containing the panel information.
M (local input) const int
On entry, M specifies the local number of rows of sub(A).
N (local input) const int
On entry, N specifies the local number of columns of sub(A).
ICOFF (global input) const int
On entry, ICOFF specifies the row and column offset of sub(A) in A.
WORK (local workspace) double *
On entry, WORK is a workarray of size at least 2*(4+2*N0).

HPL_dlocmax (3), HPL_dlocswpN (3), HPL_dlocswpT (3), HPL_pdmxswp (3), HPL_pdpancrN (3), HPL_pdpancrT (3), HPL_pdpanllN (3), HPL_pdpanllT (3), HPL_pdpanrlN (3), HPL_pdpanrlT (3), HPL_pdrpancrN (3), HPL_pdrpancrT (3), HPL_pdrpanllN (3), HPL_pdrpanrlN (3), HPL_pdrpanrlT (3), HPL_pdfact (3).
December 2, 2018 HPL 2.3

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.