Class: Quasi::Halton

Inherits:
LowDiscrepancySequence show all
Defined in:
lib/halton.rb

Instance Method Summary collapse

Methods inherited from LowDiscrepancySequence

#L2_discrepancy, #n_inverse, #nextQuasiNormalVector, #product, #productSQ, #projectionOut, #restart

Constructor Details

#initialize(dim) ⇒ Halton

Returns a new instance of Halton.



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# File 'lib/halton.rb', line 12

def initialize(dim)
  super(dim)
  compute_primes()
  @x=NArray.float(dim)
end

Instance Method Details

#compute_primes ⇒ Object 



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# File 'lib/halton.rb', line 18

def compute_primes()
  @prime= NArray.int(@dim)
  @prime[0]=2
  if(@dim>1) 
    @prime[1]=3
  end
     
  if(@dim>2) 
    @prime[2]=5
  end
  
  for j in 3..@dim
    q=@prime[j-1]+2
    while !isPrime(q) do
      q+=1
    end
    @prime[j]=q
  end
        
end

#getName ⇒ Object 



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# File 'lib/halton.rb', line 84

def getName
  return "Halton Sequence"  
end

#isPrime(q) ⇒ Object 



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# File 'lib/halton.rb', line 39

def isPrime(q)
  is_prime=false
  m=Math.sqrt(q).to_int
  i=0
  p=@prime[i]
  
  while(p<=m) do
    if(q%p==0)
      return false
    end
    i+=1
    p=@prime[i]  
  end
  return true
end

#nextPoint ⇒ Object 



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# File 'lib/halton.rb', line 78

def nextPoint
  n=@index
  @index+=1
  return pointO(n)
end

#point(n, s) ⇒ Object

THE HALTON POINTS



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# File 'lib/halton.rb', line 57

def point(n,s)
  p=@prime[s]
  x,f = 0.0,1.0
  
  while (n>0)
    f/=p
    x+=(n%p)*f
    n=n/p
  end
  
  return x
end

#pointO(n) ⇒ Object 



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# File 'lib/halton.rb', line 70

def pointO(n)
  x=Array.new(@dim)
  for s in 0..@dim-1 #@dim-1 here
    x[s]=point(n,s)
  end
  return x
end