git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@26 f3b2605a-c512-4ea7-a41b-209d697bcdaa

2006-09-27 19:51:33 +00:00
parent 3422cb245c
commit 222c95507e
536 changed files with 108384 additions and 0 deletions
--- a/src/random_mars.cpp
+++ b/src/random_mars.cpp
@ -0,0 +1,111 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   www.cs.sandia.gov/~sjplimp/lammps.html
+   Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under 
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+// Marsaglia random number generator
+
+#include "math.h"
+#include "random_mars.h"
+#include "error.h"
+
+/* ---------------------------------------------------------------------- */
+
+RanMars::RanMars(int seed)
+{
+  int ij,kl,i,j,k,l,ii,jj,m;
+  double s,t;
+      
+  if (seed == 0) error->all("Marsaglia RNG cannot use 0 seed");
+
+  u = new double[97+1];
+
+  ij = (seed-1)/30082;
+  kl = (seed-1) - 30082*ij;
+  i = (ij/177) % 177 + 2;
+  j = ij %177 + 2;
+  k = (kl/169) % 178 + 1;
+  l = kl % 169;
+  for (ii = 1; ii <= 97; ii++) {
+    s = 0.0;
+    t = 0.5;
+    for (jj = 1; jj <= 24; jj++) {
+      m = ((i*j) % 179)*k % 179;
+      i = j;
+      j = k;
+      k = m;
+      l = (53*l+1) % 169;
+      if ((l*m) % 64 >= 32) s = s + t;
+      t = 0.5*t;
+    }
+    u[ii] = s;
+  }
+  c = 362436.0 / 16777216.0;
+  cd = 7654321.0 / 16777216.0;
+  cm = 16777213.0 / 16777216.0;
+  i97 = 97;
+  j97 = 33;
+  uniform();
+}
+
+/* ---------------------------------------------------------------------- */
+
+RanMars::~RanMars()
+{
+  delete [] u;
+}
+
+/* ----------------------------------------------------------------------
+   uniform RN 
+------------------------------------------------------------------------- */
+
+double RanMars::uniform()
+{
+  double uni = u[i97] - u[j97];
+  if (uni < 0.0) uni += 1.0;
+  u[i97] = uni;
+  i97--;
+  if (i97 == 0) i97 = 97;
+  j97--;
+  if (j97 == 0) j97 = 97;
+  c -= cd;
+  if (c < 0.0) c += cm;
+  uni -= c;
+  if (uni < 0.0) uni += 1.0;
+  return uni;
+}
+
+/* ----------------------------------------------------------------------
+   gaussian RN 
+------------------------------------------------------------------------- */
+
+double RanMars::gaussian()
+{
+  double first,v1,v2,rsq,fac;
+
+  if (!save) {
+    int again = 1;
+    while (again) {
+      v1 = 2.0*uniform()-1.0;
+      v2 = 2.0*uniform()-1.0;
+      rsq = v1*v1 + v2*v2;
+      if (rsq < 1.0 && rsq != 0.0) again = 0;
+    }
+    fac = sqrt(-2.0*log(rsq)/rsq);
+    second = v1*fac;
+    first = v2*fac;
+    save = 1;
+  } else {
+    first = second;
+    save = 0;
+  }
+  return first;
+}