40 lines
1.1 KiB
Tcl
40 lines
1.1 KiB
Tcl
package require Tcl 8.5
|
|
# Uses the Box-Muller transform to compute a pair of normal random numbers
|
|
proc tcl::mathfunc::nrand {mean stddev} {
|
|
variable savednormalrandom
|
|
if {[info exists savednormalrandom]} {
|
|
return [expr {$savednormalrandom*$stddev + $mean}][unset savednormalrandom]
|
|
}
|
|
set r [expr {sqrt(-2*log(rand()))}]
|
|
set theta [expr {2*3.1415927*rand()}]
|
|
set savednormalrandom [expr {$r*sin($theta)}]
|
|
expr {$r*cos($theta)*$stddev + $mean}
|
|
}
|
|
proc stats {size {slotfactor 10}} {
|
|
set sum 0.0
|
|
set sum2 0.0
|
|
for {set i 0} {$i < $size} {incr i} {
|
|
set r [expr { nrand(0.5, 0.2) }]
|
|
|
|
incr histo([expr {int(floor($r*$slotfactor))}])
|
|
set sum [expr {$sum + $r}]
|
|
set sum2 [expr {$sum2 + $r**2}]
|
|
}
|
|
set mean [expr {$sum / $size}]
|
|
set stddev [expr {sqrt($sum2/$size - $mean**2)}]
|
|
puts "$size numbers"
|
|
puts "Mean: $mean"
|
|
puts "StdDev: $stddev"
|
|
foreach i [lsort -integer [array names histo]] {
|
|
puts [string repeat "*" [expr {$histo($i)*350/int($size)}]]
|
|
}
|
|
}
|
|
|
|
stats 100
|
|
puts ""
|
|
stats 1000
|
|
puts ""
|
|
stats 10000
|
|
puts ""
|
|
stats 100000 20
|