[andersking]

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)

         //- Construct given seed
         Random(const label&);
+       Random();
 
 
     // Member functions

(in Random.C)

  // construct given seed
 Random::Random(const label& seed)
 {
+    
+    static bool initialised = 0;
+
     if (seed > 1)
     {
         Seed = seed;

...

+    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

Random random();
scalar randno = random.scalar01();

where ever you need it.

Am i missing something?

Cheers,
Andrew

[sisetrun]

Hey Andrew,

your suggestion is exactly what I am looking for...

Could you please offer the whole part from Random.C since I get an error

my_test.C:52:28: error: request for member ‘scalar01’ in ‘random’, which is of non-class type ‘Foam::Random()’
     scalar randno = random.scalar01();
                            ^
my_test.C:52:12: warning: unused variable ‘randno’ [-Wunused-variable]
     scalar randno = random.scalar01();
            ^

I added the new mylibOpenFOAM.so to my solver...

Thanks

Best wishes

Sebastian