CFD Online Discussion Forums - Globally instantiated "Random"

Hi All,

I have a solver that I have I built that uses random numbers in a number of places. In the existing code, if a new "Random()" object is instantiated in more than one place, the random numbers are re-seeded (usually with the same seed) every time a new object is created.

In 1.5.x I changed Random() to initialise it self, and only reseed if explicitly asked. As follows:

(in Random.H)

Code:

         //- Construct given seed

         Random(const label&);

+       Random();

 

 

     // Member functions

(in Random.C)

Code:

  // construct given seed

 Random::Random(const label& seed)

 {

+    

+    static bool initialised = 0;

+

     if (seed > 1)

     {

         Seed = seed;

...

Code:

+    if (!initialised) {

#       ifdef USE_RANDOM

            srandom((unsigned int)Seed);

#       else

            srand48(Seed);

#       endif

+        initialised = 1;

+    } 

 

 }

 

+Random::Random() 

+{

+        Random(1);

+}

+

 

 int Random::bit()

I am in the process of testing the solver in 1.6.x (git), and am about to port my changes to it.

But before I do, i need to know if what I am doing is a good idea?
will this have any unforseen side effects? (so far I haven't come across any).

Is it worth including upstream?

It should be entirely compatible with existing code, but allows you to grab a random number anywhere by using

Code:

Random random();

scalar randno = random.scalar01();

where ever you need it.

Am i missing something?

Cheers,
Andrew