.\" $Id: pvm_hostsync.3,v 1.1 1996/09/23 22:01:35 pvmsrc Exp $
.TH HOSTSYNC 3PVM "20 February, 1994" "" "PVM Version 3.4"
.SH NAME
pvm_hostsync \- Get time-of-day clock from PVM host.

.SH SYNOPSIS
.nf
.ft B
.nf
C	#include <sys/time.h>
.br
	int info = pvm_hostsync( int host, struct timeval *clk,
.br
		struct timeval *delta )
.br

Fortran	call pvmfhostsync( host, clksec, clkusec, deltasec, deltausec, info )
.fi

.SH PARAMETERS
.IP host 0.8i
TID of host.
.br
.IP clk
(or \fIclksec\fR and \fIclkusec\fR)
Returns time-of-day clock sample from host.
.br
.IP delta
(or \fIdeltasec\fR and \fIdeltausec\fR)
Returns difference between local clock and remote host clock.

.SH DESCRIPTION
\fIpvm_hostsync\fR
samples the time-of day clock of a host in the virtual machine
and returns both the clock value and the difference between
local and remote clocks.
.PP
To reduce the delta error due to message transit time,
local clock samples are taken before and after reading the remote clock.
Delta is the difference between the mean local clocks and remote clock.
.PP
Note that the delta time can be negative.
The microseconds field is always normalized to 0..999999,
while the sign of the seconds field gives the sign of the delta.
For example:
.br
	3.25 Sec =  3,250000
.br
	0        =  0,0
.br
	-1 uSec  = -1,999999
.br
	-1 Sec   = -1,000000
.br
	-1.1 Sec = -2,999000
.PP
In C,
if \fIclk\fR or \fIdelta\fR is a null pointer,
that parameter is not returned.

.SH ERRORS
If pvm_hostsync is successful,
it returns PvmOk.
These error conditions can be returned by
.I pvm_hostsync
.IP PvmSysErr
pvmd not responding.
.IP PvmNoHost
specified host not in virtual machine.
.IP PvmHostFail
host is unreachable (and thus possibly failed)
.PP
.SH SEE ALSO
pvm_config(3PVM)