eo/src/eoNegExp.h

@@ -0,0 +1,50 @@
+// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+//-----------------------------------------------------------------------------
+// eoNegExp.h
+// (c) GeNeura Team, 1998
+//-----------------------------------------------------------------------------
+
+#ifndef _EONEGEXP_H
+#define _EONEGEXP_H
+
+//-----------------------------------------------------------------------------
+
+#include <time.h>
+#include <stdlib.h> 
+
+#include <math.h>
+
+#include <eoRnd.h> // for base class
+
+//-----------------------------------------------------------------------------
+// Class eoNegExp
+//-----------------------------------------------------------------------------
+
+/// Generates random numbers using a negative exponential distribution
+template<class T>
+class eoNegExp: public eoRnd<T>
+{
+ public:
+  /**
+   * Default constructor.
+   * @param _mean  Dsitribution mean
+   */
+  eoNegExp(T _mean): eoRnd<T>(), mean(_mean) {};
+
+  /**
+   * Copy constructor.
+   * @param _rnd the copyee
+   */
+  eoNegExp( const eoNegExp& _rnd): eoRnd<T>( _rnd), mean(_rnd.mean) {};
+  
+  /// Returns an uniform dandom number over the interval [min, max).
+  virtual T operator()() { return - mean*log((double)rand() / RAND_MAX); }
+  
+ private:
+  T mean;
+};
+
+//-----------------------------------------------------------------------------
+
+#endif