rivet/rivet-tcl/random.tcl

###
## random [seed | value ]
##
##    Generate a random number using only Tcl code.  This proc tries to
##    emulate what the TclX random function does.  If we don't have TclX
##    though, this is a decent substitute.
##
## Note: random predates the existence of Tcl's built-in rand() function,
## that is a part of the expr command -- programmers should consider using
## Tcl's built-in rand() function as an alternative to this command.
##
## $Id$
##
###

namespace eval ::rivet {

    proc random {args} {
        global _ran

        if {[llength $args] > 1} {
            set _ran [lindex $args 1]
        } else {
            set period 233280
            if {[info exists _ran]} {
                set _ran [expr { ($_ran*9301 + 49297) % $period }]
            } else {
                set _ran [expr { [clock seconds] % $period } ]
            }
            return [expr { int($args*($_ran/double($period))) } ]
        }
    }

}