1 files changed, 146 insertions, 0 deletions
diff --git a/gsl-1.9/rng/ran2.c b/gsl-1.9/rng/ran2.c
new file mode 100644
index 0000000..ec6d38d
--- /dev/null
+++ b/gsl-1.9/rng/ran2.c
@@ -0,0 +1,146 @@
+/* rng/ran2.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 James Theiler, Brian Gough
+ * 
+ * This program 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 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <gsl/gsl_rng.h>
+
+/* This is an implementation of the algorithm used in Numerical
+   Recipe's ran2 generator.  It is a L'Ecuyer combined recursive
+   generator with a 32-element shuffle-box.
+
+   As far as I can tell, in general the effects of adding a shuffle
+   box cannot be proven theoretically, so the period of this generator
+   is unknown. 
+
+   The period of the underlying combined generator is O(2^60). */
+
+static inline unsigned long int ran2_get (void *vstate);
+static double ran2_get_double (void *vstate);
+static void ran2_set (void *state, unsigned long int s);
+
+static const long int m1 = 2147483563, a1 = 40014, q1 = 53668, r1 = 12211;
+static const long int m2 = 2147483399, a2 = 40692, q2 = 52774, r2 = 3791;
+
+#define N_SHUFFLE 32
+#define N_DIV (1 + 2147483562/N_SHUFFLE)
+
+typedef struct
+  {
+    unsigned long int x;
+    unsigned long int y;
+    unsigned long int n;
+    unsigned long int shuffle[N_SHUFFLE];
+  }
+ran2_state_t;
+
+static inline unsigned long int
+ran2_get (void *vstate)
+{
+  ran2_state_t *state = (ran2_state_t *) vstate;
+
+  const unsigned long int x = state->x;
+  const unsigned long int y = state->y;
+
+  long int h1 = x / q1;
+  long int t1 = a1 * (x - h1 * q1) - h1 * r1;
+
+  long int h2 = y / q2;
+  long int t2 = a2 * (y - h2 * q2) - h2 * r2;
+
+  if (t1 < 0)
+    t1 += m1;
+
+  if (t2 < 0)
+    t2 += m2;
+
+  state->x = t1;
+  state->y = t2;
+
+  {
+    unsigned long int j = state->n / N_DIV;
+    long int delta = state->shuffle[j] - t2;
+    if (delta < 1)
+      delta += m1 - 1;
+    state->n = delta;
+    state->shuffle[j] = t1;
+  }
+
+  return state->n;
+}
+
+static double
+ran2_get_double (void *vstate)
+{
+  float x_max = 1 - 1.2e-7f ; /* Numerical Recipes version of 1-FLT_EPS */
+
+  float x = ran2_get (vstate) / 2147483563.0f ;
+ 
+  if (x > x_max) 
+    return x_max ;
+  
+  return x ;
+}
+
+static void
+ran2_set (void *vstate, unsigned long int s)
+{
+  ran2_state_t *state = (ran2_state_t *) vstate;
+  int i;
+
+  if (s == 0)
+    s = 1;      /* default seed is 1 */
+
+  state->y = s;
+
+  for (i = 0; i < 8; i++)
+    {
+      long int h = s / q1;
+      long int t = a1 * (s - h * q1) - h * r1;
+      if (t < 0)
+        t += m1;
+      s = t;
+    }
+
+  for (i = N_SHUFFLE - 1; i >= 0; i--)
+    {
+      long int h = s / q1;
+      long int t = a1 * (s - h * q1) - h * r1;
+      if (t < 0)
+        t += m1;
+      s = t;
+      state->shuffle[i] = s;
+    }
+
+  state->x = s;
+  state->n = s;
+
+  return;
+}
+
+static const gsl_rng_type ran2_type =
+{"ran2",                        /* name */
+ 2147483562,                    /* RAND_MAX */
+ 1,                             /* RAND_MIN */
+ sizeof (ran2_state_t),
+ &ran2_set,
+ &ran2_get,
+ &ran2_get_double};
+
+const gsl_rng_type *gsl_rng_ran2 = &ran2_type;