randomGenerator: Renamed Random

src/OpenFOAM/primitives/randomGenerator/randomGenerator.C

@@ -0,0 +1,109 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2018-2024 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "randomGenerator.H"
+#include "PstreamReduceOps.H"
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+Foam::scalar Foam::randomGenerator::scalarNormal()
+{
+    // Proper inversion of the distribution. Slow. Exactly maintains
+    // the random behaviour of the generator.
+
+    /*
+    using namespace constant::mathematical;
+
+    static const scalar sqrtTwo = sqrt(scalar(2));
+    static const scalar sqrtPiByTwo = sqrt(pi)/2;
+    static const scalar a = 8*(pi - 3)/(3*pi*(4 - pi));
+
+    const scalar x = 2*scalar01() - 1;
+    const scalar xPos = mag(x);
+
+    // Initial approximation
+    const scalar l = log(1 - sqr(xPos));
+    const scalar ll = 2/(pi*a) + l/2;
+    scalar y = sqrt(sqrt(sqr(ll) - l/a) - ll);
+
+    // Newton improvement
+    label n = 0;
+    while (n < 2)
+    {
+        const scalar dt = (erf(y) - xPos)/exp(- y*y)*sqrtPiByTwo;
+        y -= dt;
+        n += mag(dt) < rootSmall;
+    }
+
+    return sign(x)*sqrtTwo*y;
+    */
+
+    // Box-Muller transform. Fast. Uses rejection and caching so the
+    // random sequence is not guaranteed.
+
+    if (scalarNormalStored_)
+    {
+        scalarNormalStored_ = false;
+
+        return scalarNormalValue_;
+    }
+    else
+    {
+        scalar x1, x2, rr;
+
+        do
+        {
+            x1 = 2*scalar01() - 1;
+            x2 = 2*scalar01() - 1;
+            rr = sqr(x1) + sqr(x2);
+        }
+        while (rr >= 1 || rr == 0);
+
+        const scalar f = sqrt(- 2*log(rr)/rr);
+
+        scalarNormalValue_ = x1*f;
+        scalarNormalStored_ = true;
+
+        return x2*f;
+    }
+}
+
+
+Foam::scalar Foam::randomGenerator::globalScalar01()
+{
+    scalar value = - vGreat;
+
+    if (Pstream::master())
+    {
+        value = scalar01();
+    }
+
+    Pstream::scatter(value);
+
+    return value;
+}
+
+
+// ************************************************************************* //