[ns] Bug in Error Model Tcl lib file

[Sven Ostring <ostrinsa@elec.canterbury.ac.nz>]

There is a bug in the Error Model Tcl lib file---the ErrorModel/TwoStateMarkov 
class is initialised incorrectly:

Class ErrorModel/TwoStateMarkov -superclass ErrorModel/TwoState

ErrorModel/TwoStateMarkov instproc init {rate eu {transition}} {
	$self next
	$self unit time

	set rv0 [new RandomVariable/Exponential]
	set rv1 [new RandomVariable/Exponential]
	$rv0 set avg_ [lindex $rate 0]
	$rv1 set avg_ [lindex $rate 1]
	$self ranvar 0 $rv0
	$self ranvar 1 $rv1

#	set p01 [lindex $transition 0]
#	set p10 [lindex $transition 1]
#	set trans [list [list [expr 1 - $p01] $p01] \
#			[list [expr 1 - $p01] $p01]]

#	# state 0 is the start state
#	$self next $states_ $trans $eu $i [lindex $states_ 0]
}

Considering that the init procedure for ErrorModel/TwoState requires the 
arguments:
ErrorModel/TwoState instproc init {rv0 rv1 {unit "pkt"}} {
	...
}

the init procedure for the TwoStateMarkov class should be as follows:

ErrorModel/TwoStateMarkov instproc init {rate eu {transition}} {
# Bug fix by Sven Ostring 2000/11/24
#	$self next
#	$self unit time

	set rv0 [new RandomVariable/Exponential]
	set rv1 [new RandomVariable/Exponential]
	$rv0 set avg_ [lindex $rate 0]
	$rv1 set avg_ [lindex $rate 1]
	set unit time
# Bug fix by Sven Ostring 2000/11/24
#	$self ranvar 0 $rv0
#	$self ranvar 1 $rv1
	$self next $rv0 $rv1 $unit

#	set p01 [lindex $transition 0]
#	set p10 [lindex $transition 1]
#	set trans [list [list [expr 1 - $p01] $p01] \
#			[list [expr 1 - $p01] $p01]]

#	# state 0 is the start state
#	$self next $states_ $trans $eu $i [lindex $states_ 0]
}

Cheers,
Sven.