Open Mash Cross Reference
mash/tcl/common/mash-rng.tcl

   Class MashRNG
   proc exponential {args} {
           eval [list MashRNG exponential] $args
   }
   
   proc uniform {args} {
           eval [list MashRNG uniform] $args
   }
   
  proc integer {args} {
          eval [list MashRNG integer] $args
  }
  
  MashRNG proc init {} {
          $self next
          #z2 used to create a normal distribution  from a uniform distribution
          #using the polar method
          $self instvar z2
          set z2 0
  }
  
  MashRNG proc seed {seed} {
          return [random $seed]
  }
  
  MashRNG proc next-random {} {
          return [random]
  }
  
  MashRNG proc uniform {a b} {
          expr $a + (($b - $a) * ([$self next-random] * 1.0 / 0x7fffffff))
  }
  
  MashRNG proc integer k {
          expr [$self next-random] % abs($k)
  }
  
  MashRNG proc exponential {{mu 1.0}} {
          expr - $mu * log(([$self next-random] + 1.0) / (0x7fffffff + 1.0))
  }
  
  MashRNG proc normal {a1 a2 } {
          $self instvar z2
          if {$z2 !=0 } {
                  set z1 $z2
                  set z2 0
          } else {
                  set w 1
                  while { $w >= 1.0 } {
                          set v1 [expr 2.0 * ([$self next-random] *1.0/0x7fffffff) - 1.0]
                          set v2 [expr 2.0 * ([$self next-random] *1.0/0x7fffffff) - 1.0]
                          set w  [expr ($v1*$v1+$v2*$v2)]
                  }
                  set w [expr  sqrt((-2.0*log($w))/$w)]
                  set z1 [expr $v1*$w]
                  set z2 [expr $v2*$w]
          }
          expr $a1 + $z1 *$a2
  }
  
  MashRNG proc lognormal {med stddev } {
          expr $med *exp($stddev*[$self normal 0.0 1.0])
  }