umontreal.iro.lecuyer.hups

Class F2wStructure

java.lang.Object

umontreal.iro.lecuyer.hups.F2wStructure

public class F2wStructure
extends java.lang.Object

This class implements methods and fields needed by the classes F2wNetLFSR, F2wNetPolyLCG, F2wCycleBasedLFSR and F2wCycleBasedPolyLCG. It also stores the parameters of these point sets which will contain 2^rw points (see the meaning of r and w below). The parameters can be stored as a polynomial P(z) over F_2^w[z]

P(z) = z^r + ∑_i=1^rb_iz^r-i

where b_i∈F_2^w for i = 1,…, r. Let ζ be the root of an irreducible polynomial Q(z)∈F₂[z]. It is well known that ζ is a generator of the finite field F_2^w. The elements of F_2^w are represented using the polynomial ordered basis (1, ζ,…, ζ^w-1).

In this class, only the non-zero coefficients of P(z) are stored. It is stored as

P(z) = z^r + ∑_i=0^nbcoeffcoeff[i]z^nocoeff[i]

where the coefficients in coeff[] represent the non-zero coefficients b_i of P(z) using the polynomial basis. The finite field F_2^w used is defined by the polynomial

Q(z) = z^w + ∑_i=1^wa_iz^w-i

where a_i∈F₂, for i = 1,…, w. Polynomial Q is stored as the bit vector modQ = (a_w,…, a₁).

The class also stores the parameter step that is used by the classes F2wNetLFSR, F2wNetPolyLCG, F2wCycleBasedLFSR and F2wCycleBasedPolyLCG. This parameter is such that the implementation of the recurrence will output a value at every step iterations.

Method Summary

Modifier and Type	Method and Description
static void	print(java.lang.String filename) Prints the content of file filename.
java.lang.String	toString() This method returns a string containing the polynomial P(z) and the stepping parameter.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

print

public static void print(java.lang.String filename)

Prints the content of file filename. See the constructor above for the conditions on filename.

toString

public java.lang.String toString()

This method returns a string containing the polynomial P(z) and the stepping parameter.

Overrides:

toString in class java.lang.Object