Re: Query: Spatially uncorrelated reproducible random values

[Jan Burse]

Dear Nigel

A stream can be generated for example by 
a formula such as:

  x(0)=1
  x(n+1)=x(n)*a mod b.

The simplest parameters that come to my
mind are a=257 and b=8191. Thus for a line 
I would then use
  
  x(n)=a^n mod b.

where x(n) is the magnitude at n. Typically 
a^n will exceed a fixed integer representation. 
But if you look for example at the Java class 
java.math.BigInteger you find the method:

   public BigInteger modPow(BigInteger exponent, BitInteger m)

Which would do the job. A generalisation to many
dimensions seems also possible. But I must admit, I 
didnt test all this.

Best Regards
--
Jan Burse                         SIAM, EAWAG
Scheuchzerstr. 67                 Überlandstr. 133
8006 Zürich                       8600 Dübendorf
tel: +41-1-364 17 66              tel: +41-1-823 55 34


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