1 files changed, 161 insertions, 0 deletions
diff --git a/gsl-1.9/rng/ranf.c b/gsl-1.9/rng/ranf.c
new file mode 100644
index 0000000..cc5ac41
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+++ b/gsl-1.9/rng/ranf.c
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+/* rng/ranf.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 <math.h>
+#include <stdlib.h>
+#include <gsl/gsl_rng.h>
+
+/* This is the CRAY RANF generator. The generator returns the
+   upper 32 bits from each term of the sequence,
+
+   x_{n+1} = (a x_n) mod m 
+
+   using 48-bit unsigned arithmetic, with a = 0x2875A2E7B175 and m =
+   2^48. The seed specifies the lower 32 bits of the initial value,
+   x_1, with the lowest bit set (to prevent the seed taking an even
+   value), and the upper 16 bits set to 0.
+
+   There is a subtlety in the implementation of the seed. The initial
+   state is put one step back by multiplying by the modular inverse of
+   a mod m. This is done for compatibility with the original CRAY
+   implementation.
+
+   Note, you can only seed the generator with integers up to 2^32,
+   while the CRAY uses wide integers which can cover all 2^48 states
+   of the generator.
+
+   The theoretical value of x_{10001} is 141091827447341.
+
+   The period of this generator is 2^{46}. */
+
+static inline void ranf_advance (void *vstate);
+static unsigned long int ranf_get (void *vstate);
+static double ranf_get_double (void *vstate);
+static void ranf_set (void *state, unsigned long int s);
+
+static const unsigned short int a0 = 0xB175 ;
+static const unsigned short int a1 = 0xA2E7 ;
+static const unsigned short int a2 = 0x2875 ;
+
+typedef struct
+  {
+    unsigned short int x0, x1, x2;
+  }
+ranf_state_t;
+
+static inline void
+ranf_advance (void *vstate)
+{
+  ranf_state_t *state = (ranf_state_t *) vstate;
+
+  const unsigned long int x0 = (unsigned long int) state->x0 ;
+  const unsigned long int x1 = (unsigned long int) state->x1 ;
+  const unsigned long int x2 = (unsigned long int) state->x2 ;
+
+  unsigned long int r ;
+  
+  r = a0 * x0 ;
+  state->x0 = (r & 0xFFFF) ;
+ 
+  r >>= 16 ;
+  r += a0 * x1 + a1 * x0 ;
+  state->x1 = (r & 0xFFFF) ;
+  
+  r >>= 16 ;
+  r += a0 * x2 + a1 * x1 + a2 * x0 ;
+  state->x2 = (r & 0xFFFF) ;
+}
+
+static unsigned long int 
+ranf_get (void *vstate)
+{
+  unsigned long int x1, x2;
+
+  ranf_state_t *state = (ranf_state_t *) vstate;
+  ranf_advance (state) ;  
+
+  x1 = (unsigned long int) state->x1;
+  x2 = (unsigned long int) state->x2;
+  
+  return (x2 << 16) + x1;
+}
+
+static double
+ranf_get_double (void * vstate)
+{
+  ranf_state_t *state = (ranf_state_t *) vstate;
+
+  ranf_advance (state) ; 
+
+  return (ldexp((double) state->x2, -16)
+          + ldexp((double) state->x1, -32) 
+          + ldexp((double) state->x0, -48)) ;
+}
+
+static void
+ranf_set (void *vstate, unsigned long int s)
+{
+  ranf_state_t *state = (ranf_state_t *) vstate;
+
+  unsigned short int x0, x1, x2 ;
+  unsigned long int r ;
+
+  unsigned long int b0 = 0xD6DD ;
+  unsigned long int b1 = 0xB894 ;
+  unsigned long int b2 = 0x5CEE ;
+
+  if (s == 0)  /* default seed */
+    {
+      x0 = 0x9CD1 ;
+      x1 = 0x53FC ;
+      x2 = 0x9482 ;
+    }
+  else 
+    {
+      x0 = (s | 1) & 0xFFFF ;
+      x1 = s >> 16 & 0xFFFF ;
+      x2 = 0 ;
+    }
+
+  r = b0 * x0 ;
+  state->x0 = (r & 0xFFFF) ;
+ 
+  r >>= 16 ;
+  r += b0 * x1 + b1 * x0 ;
+  state->x1 = (r & 0xFFFF) ;
+  
+  r >>= 16 ;
+  r += b0 * x2 + b1 * x1 + b2 * x0 ;
+  state->x2 = (r & 0xFFFF) ;
+
+  return;
+}
+
+static const gsl_rng_type ranf_type =
+{"ranf",                        /* name */
+ 0xffffffffUL,                  /* RAND_MAX */
+ 0,                             /* RAND_MIN */
+ sizeof (ranf_state_t),
+ &ranf_set,
+ &ranf_get,
+ &ranf_get_double
+};
+
+const gsl_rng_type *gsl_rng_ranf = &ranf_type;